Whether you are working on a new building or a renovation,
problems may arise with the quality of the water.
Pesticides, cleaning solvents, and seepage from landfills
pollute groundwater in some rural areas of the United
In urban areas, the level of chlorine
added to prevent bacterial contamination sometimes results
in bad tasting water and deterioration of pipes and
plumbing fixtures.
Electric power plants discharge great amounts of
waste heat into water, which can change biological and
chemical conditions and threaten fish. Steel, paper, and
textiles are the most polluting industries. The textile industry
employs large quantities of water in fiber production
and processing and in fabric finishing, especially
dyeing. As a designer, you have the power to avoid
products whose manufacturing includes highly toxic
technologies, and to seek out ones with low environmental
impact.
WATER QUALITY CHARACTERISTICS
How do you tell whether the water you drink is safe?
Communities routinely check on the quality of their
municipal water supplies. If a home or business owner
is unsure whether his or her building’s supply meets
safety standards, a government or private water quality
analyst will provide instructions and containers for taking
samples, and assess the purity of the water supply.
The analyst’s report gives numerical values for mineral
content, acidity or alkalinity (pH level), contamination,
turbidity, total solids, and biological purity, and an
opinion on the sample’s suitability for its intended use.
Physical Characteristics
Even though cloudy or odd-smelling water may not actually
be harmful to drink, we generally object to these
physical characteristics. Turbidity—a muddy or cloudy
appearance—is caused by suspended clay, silt, or other
particles, or by plankton or other small organic material.
Color changes can be due to dissolved organic matter,
such as decaying vegetation, or other materials like
rust. Like turbidity, color changes don’t usually threaten
health. Unpleasant taste and odor can be caused by organic
materials, salts, or dissolved gases, and can often
be treated after being diagnosed. Foaming is not necessarily
a health threat, but may indicate concentrations
of detergents present in water contaminated by domestic
wastes.
Most people prefer water at a temperature of 10°C
to 16°C (50°F–60°F) for drinking. When water standing
in pipes becomes warmer, people often run it down
the drain until it cools.
When water is piped under pressure throughout the
plumbing system, air can become trapped in the water
and cause cloudiness. This is only temporary and the
water clears up in a short time. You can safely drink,
cook with, or bathe in this water. Chemical Characteristics
Groundwater dissolves minerals as it moves slowly down
through the soil and rocks. Testing individual water supplies
will detect harmful substances, corrosive chemicals,
or chemicals that may stain fixtures and clothing. Corrosion
produces scale that lines pipes and clogs openings.
It is affected by water acidity, electrical conductivity,
oxygen content, and carbon dioxide content. Acid
neutralizers and corrosion inhibitors help, along with
various preventive coatings and linings for pipes.
Tests for water pH determine relative alkalinity or
acidity. A pH of 7 is neutral, with numbers as low as
5.5 indicating acid, corrosive conditions and as high
as 9 representing alkaline conditions. If tap water stains
tubs and sinks a bluish-green, it is overly acidic, and a
neutralizing filter should be installed.
High alkaline or base levels entail bitter, slippery,
and caustic qualities and are due to the presence of bicarbonate,
carbonate, or hydroxide components. Bases
have the ability to combine with acids to make salts.
Hard water, caused by calcium and magnesium salts, inhibits
the cleaning action of soaps and detergents and
deposits scale inside hot water pipes and cooking utensils.
The simplest way to acquire a supply of soft water
for washing clothes is to collect rainwater in a cistern.
Toxic substances, including arsenic, barium, cadmium,
chromium, cyanides, fluoride, lead, selenium,
and silver, sometimes contaminate water. Lead poses the
greatest threat to infants and young children with developing
nervous systems. It is possible that lead levels
in one home may be higher than levels at other homes
in the same community as a result of lead solder or
pipes used in the plumbing. Infants and children who
drink water with high levels of lead may experience delays
in their physical or mental development, showing
slight deficits in attention span and learning abilities.
Adults who drink this water over many years may develop
kidney problems or high blood pressure. If you
are concerned about a possibility of elevated lead levels
in a water supply, you should have the water tested
(municipal water utilities will usually do this for you).
Flushing the tap for 30 seconds to two minutes before
using the water will help the water supply stay fresh, but
wastes a lot of water. Don’t use hot water from the faucet
for drinking or cooking, especially when making baby
formula or other food for infants.
Arsenic occurs naturally in some water supplies. Arsenic
in water can cause symptoms such as dry, hacking
coughs and burning hands and feet, and increases the
risk of lung, skin, or bladder cancer. A federal study in
2000 of the water supply in Fallon, Nevada, showed that
customers were exposed to 90 parts per billion (ppb) of
arsenic, more than any other large system. This is almost
Agricultural Runoff Leaking Gas Tank
Agricultural Runoff
Well
Chemical Dump
Liquid Industrial Waste
Aquifer
Bedrock
Water
Table
Groundwater contamination.
twice the standard set in 1975, and nine times the
amount currently recommended by scientists and public
health doctors. Even if the community supply is
cleaned up, residents outside city limits rely on private
wells where the arsenic frequently reaches 700 ppb and
up to 2000 ppb.
Seepage of drainage from livestock manure can contaminate
shallow wells with nitrates, which in high
concentrations cause a condition commonly known as
“blue baby” disease in infants. Wells near homes treated
for termites may contain pesticides.
Chlorides from marine sediments, brine, seawater,
or industrial or domestic wastes can affect the taste of
groundwater. When copper enters the water supply from
natural deposits or from corrosion of copper piping, it
gives the water an undesirable taste.
Iron is frequently present in groundwater, or from
corroded iron pipes. Changes in water speed or direction
in local pipes can carry rust along. This can happen
when the valves are being repaired, the system is
being flushed or tested, or fire hydrants are in use. Iron
produces a red, brown, or yellow color in water, and can
cause brownish stains on washed clothes. Iron affects
the water’s taste, but it is not harmful to health.
Iron manganese is similar in color and taste to iron
and acts as a natural laxative. Sulfates from natural deposits
of Epsom salts or Glauber’s salts are also natural
laxatives. Zinc is derived from natural deposits. Zinc
does not pose a health threat but leaves an undesirable
taste.
Too much sodium in water may be dangerous for
people with heart, kidney, or circulatory problems who
need to observe low-sodium diets. Sodium can enter
water through salts used for ice on roads. Some water
softeners also increase sodium levels.
Biological Contaminants
Disease-producing organisms, such as bacteria, protozoa,
and viruses, are sometimes found in water. A positive
test for one particular kind of bacteria that is present
in the fecal wastes of humans and many animals
and birds—E. coli—indicates possible problems with
others. Coliform bacteria, including E. coli, outnumber
all other disease-producing organisms in water.
To avoid the growth of coliform bacteria, communities
choose water sources without much plant or animal
life, such as groundwater rather than surface water,
and try to keep human activity away from watersheds
(the areas that drain into the water supply) to protect
against contamination. Fertilizers and nutrient minerals
from farms and lawns can encourage bacterial growth.
Water stored in the dark and at low temperatures is less
likely to promote bacteria. When microorganisms do get
into the water supply, they are destroyed at water treatment
facilities.
Sometimes microorganisms do not pose a health
danger, but multiply and clog pipes and filters. They can
affect the water’s appearance, odor, and taste. Surface
water reservoirs may contain algae. Cooling towers can
also have high bacterial counts.
Radiological Characteristics
Radioactivity from mining and radioactive material used
in industry, power plants, and military installations can
contaminate water. Even low concentrations pose a danger
because radioactive contamination accumulates in
the body over time.
WATER TREATMENTS
It is best to prevent contamination of safe water supplies,
and conserve them for high-quality uses. When all
else fails, water is treated. Distillation, the process of
heating water to produce water vapor, is a simple, lowtech
way to eliminate pollution and purify water for
drinking, cooking, and laboratory use. Distilled water is
pure but has a flat taste.
The most important health-related water treatment
is disinfection to destroy microorganisms. It is required
for surface water, or for groundwater in contact with surface
water. Primary water treatment begins with filtration,
followed by disinfection to kill microorganisms
in the water. Secondary treatment keeps the level of disinfectant
high enough to prevent microorganism regrowth.
Disinfection is accomplished by a variety of
means, including chlorination, nanofiltration (filtration
for extremely small organisms), ultraviolet (UV) light,
bromine, iodine, ozone, and heat treatment.
Suspended particles and some materials affecting
color or taste can be removed by filtration. Filters can
also remove some bacteria, including Giardia cysts. The
water is passed through permeable fabric or porous beds
of filtering material.
Aeration, also called oxidation, improves taste and
color and helps to remove iron and manganese. Water
is sprayed or run down turbulent waterfalls to expose as
much of its surface to air as possible. Sculptural waterfalls
called flowforms, which have rhythmical, pulsating,
or figure-8 patterns, are both efficient and beautiful.
The retailer Real Goods in Hopland, California,
uses flowforms as part of a recycled water irrigation
system. Aeration improves the flat taste of distilled and
cistern water, and removes odors from hydrogen sulfide
and algae. Aeration may make the water more
corrosive.
The addition of fluoride to public water supplies
has greatly reduced the amount of childhood tooth decay.
Once we develop our adult teeth, we no longer benefit
from the fluoride, and too much fluoride can cause
yellow mottling on the teeth.
Water Distribution
pressure. Downfeed systems raise water to storage tanks
at the top of a building, from which it drops down to
plumbing fixtures. The rooftop storage tanks may have
to be heated to prevent freezing. The water in a rooftop
storage tank is also available for fire hoses. The heavy
tank requires extra structural support.
A water storage tank shares the uppermost zone in
most high-rise buildings with two-story elevator penthouses,
chimneys, plumbing vents, exhaust blowers, and
air-conditioning cooling towers. Solar collectors for hot
water heating are sometimes also on the roof. All of this
equipment is usually surrounded by a band or screen
two or more stories high.
SUPPLY PIPES
Lead was used for plumbing pipes by the Romans 2000
years ago, and the word “plumbing” is derived from the
Latin word for lead, “plumbum.” Lead pipes were used
through the 1950s. As a result, the U.S. Environmental
Protection Agency (EPA) is concerned even today that
lead may leach out of lead pipes and copper pipes joined
with lead solder and enter the water supply. Fortunately,
lead on the inside surface of a pipe quickly reacts with
sulfates, carbonates, and phosphates in the water to
form a coating that keeps it from leaching out of the
pipe. Experts believe, however, that the lead content in
water is likely to exceed safe guidelines when the water
is highly acidic or is allowed to sit in the lead pipes for
a long time.
Plumbing supply pipes are made of copper, red
brass, galvanized steel, and plastic. Galvanized steel pipe
was the standard for water supply until copper took over
in the 1960s. Steel pipe is strong and inexpensive, but
is subject to corrosion, and eventually rusts and springs
leaks. Steel pipes last from about 20 to 50 years. Mineral
deposits build up inside, reducing the inside diameter
and resulting in reduced water pressure at
faucets.
Red brass and copper tubing offer the best corrosion
resistance, with copper being less expensive, easier
to assemble, more resistant to acids, and lighter weight
than brass. Copper pipe lasts about twice as long as galvanized
pipe. However, it costs nearly twice as much by
length. Both flexible (soft temper) and rigid copper tubing
can be soldered, but only the flexible copper tubing
will accept compression fittings or flare fittings without
soldering.
Iron (ferrous) pipes and large brass pipes use
threaded connections. Copper pipes are joined with solder.
Solder, which was formerly made of lead, is now a
tin and antimony alloy. The molten solder is drawn into
the joint. This allows piping to be set up without turning
the parts to be connected, greatly facilitating installation.
It also permits pipes with thin walls, because no
threads have to be cut into their thickness. The smooth
interiors contribute less friction to flowing water.
Plastic pipe is lightweight, low-cost, corrosion resistant,
and easy to work with. It is available in flexible
form for outdoor use, and as rigid pipe. Plastic pipe is
made from synthetic resins derived from coal and petroleum.
Rigid polyvinyl chloride (PVC, white or gray)
and acrylonitrile-butadiene-styrene (ABS, black) pipes
are suitable for various cold-water applications. Both
ABS and PVC are thermoplastics, which can be molded
under heat. Because of their sensitivity to heat, however,
ABS and PVC are not used for hot water lines.
Chlorinated PVC (CPVC) pipe, which is usually
cream color, may be used for hot or cold water. It is a
thermoplastic and can be solvent welded, but it can be
used at higher temperatures than ABS or PVC. Polybutylene
(PB) pipe cannot be welded with solvent, and
uses compression fittings. It is flexible, and can be
snaked through walls. It is also less susceptible to damage
from freezing.
More access to plastic pipes must be supplied in
case fittings need to be repaired than where soldered
joints are used with metal pipes. Plastic pipe used for
potable water is required to have a seal from the National
Sanitation Foundation (NSF). Because plastic
pipes are shockproof, they are used in mobile homes
where vibration would be a problem for other types of
plumbing.
Engineers determine pipe sizes by the rate at which
the pipes will transport water when there is the most
demand. Pipes in the supply network tend to be smaller
as they get farther from the water source and closer to
the point of use, since not all of the water has to make
the whole trip. The sizes depend on the number and
types of fixtures to be served and pressure losses due to
friction and vertical travel. Water flowing through a
smaller pipe is under greater pressure than the same
amount of water in a larger pipe. Each type of fixture is
assigned a number of fixture units. Based on the total
number of fixture units for the building, the number of
gallons per minute (gpm) is estimated. The engineer assumes
that not all the fixtures are in use at the same
time, so the total demand is not directly proportional
to the number of fixture units. The interior designer
needs to give the engineer specific information about
the number of plumbing fixtures and their requirements
as early in the process as possible.
Pipes sweat when moisture in the air condenses on
the outsides of cold pipes. The condensation drops off
the pipes, wetting and damaging finished surfaces. Cold
water pipes should be insulated to prevent condensation.
Insulation also keeps heat from adjacent warm
spaces from warming the water in the pipes. When pipes
are wrapped in glass fiber 13 to 25 mm
with a tight vapor barrier on the exterior surface, the
moisture in the air can’t get to the cold surface. Hot
water pipes are insulated to prevent heat loss. When hot
and cold water pipes run parallel to each other, they
should be a minimum of 15 cm (6 in.) apart, so that
they don’t exchange heat.
In very cold climates, water pipes in exterior walls
and unheated buildings may freeze and rupture. Avoid
locating fixtures along exterior walls for this reason. If
water supply pipes must be located in an exterior wall,
they should be placed on the warm side (inside, in a
cold climate) of the wall insulation. A drainage faucet
located at a low point will allow the pipes to be drained
before being exposed to freezing weather.
SUPPLY LINES AND VALVES
From a branch supply line, a line runs out to each fixture
(Fig. 8-2). Roughing-in is the process of getting all
the pipes installed, capped, and pressure tested before
actual fixtures are installed. The rough-in dimensions for
Water Distribution
The design for the hair salon would involve a lot of
equipment. Right from the start, Harry made sure that
the engineers had spec sheets for all his client’s equipment.
There was just one problem. The client was looking
for a special shampoo sink for the project, and was
having trouble finding a supplier.
The engineer had to specify something so that the
building department could review and approve the
plans and the contractor could submit a bid. It was decided
to specify plumbing coming up into the cabinet
behind the sink, then out horizontally to the sink. The
drawings were prepared and sent to the contractor and
building department.
Meanwhile, the client found a supplier for the
shampoo sink. Once construction began, the contractor
needed the specifications on how the sink would be
plumbed. Despite repeated calls to the sink supplier,
Harry couldn’t get technical specs for the sink.
When the sinks arrived, the contractor discovered
that they were designed to be plumbed up the pedestal
from the floor below. The plumbing was already installed
in the cabinets behind the sink. It was possible
to modify the sink to accept pipes from behind, but they
would be exposed. Harry and the contractor decided to
bring the plumbing from behind through a cutout in
the pedestal. The exposed pipes were covered by a laminate
panel to match the cabinets, giving a finished appearance
and hiding the pipes.
each plumbing fixture should be verified with the fixture
manufacturer so that fixture supports can be built
in accurately during the proper phase of construction.
It is a good idea to have a shutoff valve to control
the flow of water at each vertical pipe (known as a riser),
with branches for kitchens and baths and at the runouts
to individual fixtures. Additional valves may be installed
to isolate one or more fixtures from the water supply
system for repair and maintenance. Compression-type
globe valves are used for faucets, drain valves, and hose
connections.
A dead-end upright branch of pipe located near a
fixture is called an air chamber. When a faucet is shut
off quickly, the water’s movement in the supply pipe
drops to zero almost instantly. Without the air chamber,
the pressure in the pipe momentarily becomes very
high, and produces a sound like banging the pipe with
a hammer—appropriately called water hammer—that
may damage the system. The air chamber absorbs the
shock and prevents water hammer.
Vacuum breakers keep dirty water from flowing
back into clean supply pipes. They also isolate water
from dishwashers, clothes washers, and boilers from the
water supply.
CHILLED WATER
Most public buildings provide chilled drinking water.
Previously, a central chiller with its own piping system
was used to distribute the cold water. More recently,
water is chilled in smaller water coolers at each point
of use, providing better quality at less cost. A pump constantly
circulates the chilled water, so you don’t have to
wait for the water to get cold. The chilled water piping
must be covered with insulation in a vapor-tight wrap
to avoid condensation.
Domestic hot water (DHW) is hot water that is used for
bathing, clothes washing, washing dishes, and many
other things, but not for heating building spaces. Domestic
hot water is sometimes called building service
hot water in nonresidential uses. Sometimes, when a
well-insulated building uses very little water for space
heating but uses a lot of hot water for other purposes,
a single large hot water heater supplies both.
HOT WATER TEMPERATURES
Excessively hot water temperatures can result in scalding.
People generally take showers at 41°C to 49°C
(105°F–120°F), often by blending hot water at 60°C
(140°F) with cold water with a mixing valve in the
shower. Most people experience temperatures above
43°C (110°F) as uncomfortably hot.
Some commercial uses require higher temperatures.
The minimum for a sanitizing rinse for a commercial
dishwasher or laundry is 82°C (180°F). Generalpurpose
cleaning and food preparation requires 60°C
(140°F) water. Temperatures above 60°C can cause serious
burns, and promote scaling if the water is hard.
However, high temperatures limit the growth of the
harmful bacterium Legionella pneumophila, which causes
Legionnaire’s disease. Water heaters for high temperature
uses have larger heating units, but the tanks can
be smaller because less cold water has to be mixed in.
Some appliances, such as dishwashers, heat water at the
point of use. Codes may regulate or limit high water
temperatures.
Lower temperatures are less likely to cause burns,
but may be inadequate for sanitation. Lower temperature
water loses less heat in storage and in pipes, saving
energy. Smaller heating units are adequate, but larger
storage tanks are needed. Solar or waste heat recovery
sources work better with lower temperature water
heaters. For energy conservation, use the lowest possible
temperatures.
WATER HEATERS
Water heating accounts for over 20 percent of the average
family’s annual heating bill. Hot water is commonly
heated using natural gas or electricity. It is also possible
to use heat that would be wasted from other systems,
or heat from steam, cogeneration, or wood-burning
systems.
problems may arise with the quality of the water.
Pesticides, cleaning solvents, and seepage from landfills
pollute groundwater in some rural areas of the United
In urban areas, the level of chlorine
added to prevent bacterial contamination sometimes results
in bad tasting water and deterioration of pipes and
plumbing fixtures.
Electric power plants discharge great amounts of
waste heat into water, which can change biological and
chemical conditions and threaten fish. Steel, paper, and
textiles are the most polluting industries. The textile industry
employs large quantities of water in fiber production
and processing and in fabric finishing, especially
dyeing. As a designer, you have the power to avoid
products whose manufacturing includes highly toxic
technologies, and to seek out ones with low environmental
impact.
WATER QUALITY CHARACTERISTICS
How do you tell whether the water you drink is safe?
Communities routinely check on the quality of their
municipal water supplies. If a home or business owner
is unsure whether his or her building’s supply meets
safety standards, a government or private water quality
analyst will provide instructions and containers for taking
samples, and assess the purity of the water supply.
The analyst’s report gives numerical values for mineral
content, acidity or alkalinity (pH level), contamination,
turbidity, total solids, and biological purity, and an
opinion on the sample’s suitability for its intended use.
Physical Characteristics
Even though cloudy or odd-smelling water may not actually
be harmful to drink, we generally object to these
physical characteristics. Turbidity—a muddy or cloudy
appearance—is caused by suspended clay, silt, or other
particles, or by plankton or other small organic material.
Color changes can be due to dissolved organic matter,
such as decaying vegetation, or other materials like
rust. Like turbidity, color changes don’t usually threaten
health. Unpleasant taste and odor can be caused by organic
materials, salts, or dissolved gases, and can often
be treated after being diagnosed. Foaming is not necessarily
a health threat, but may indicate concentrations
of detergents present in water contaminated by domestic
wastes.
Most people prefer water at a temperature of 10°C
to 16°C (50°F–60°F) for drinking. When water standing
in pipes becomes warmer, people often run it down
the drain until it cools.
When water is piped under pressure throughout the
plumbing system, air can become trapped in the water
and cause cloudiness. This is only temporary and the
water clears up in a short time. You can safely drink,
cook with, or bathe in this water. Chemical Characteristics
Groundwater dissolves minerals as it moves slowly down
through the soil and rocks. Testing individual water supplies
will detect harmful substances, corrosive chemicals,
or chemicals that may stain fixtures and clothing. Corrosion
produces scale that lines pipes and clogs openings.
It is affected by water acidity, electrical conductivity,
oxygen content, and carbon dioxide content. Acid
neutralizers and corrosion inhibitors help, along with
various preventive coatings and linings for pipes.
Tests for water pH determine relative alkalinity or
acidity. A pH of 7 is neutral, with numbers as low as
5.5 indicating acid, corrosive conditions and as high
as 9 representing alkaline conditions. If tap water stains
tubs and sinks a bluish-green, it is overly acidic, and a
neutralizing filter should be installed.
High alkaline or base levels entail bitter, slippery,
and caustic qualities and are due to the presence of bicarbonate,
carbonate, or hydroxide components. Bases
have the ability to combine with acids to make salts.
Hard water, caused by calcium and magnesium salts, inhibits
the cleaning action of soaps and detergents and
deposits scale inside hot water pipes and cooking utensils.
The simplest way to acquire a supply of soft water
for washing clothes is to collect rainwater in a cistern.
Toxic substances, including arsenic, barium, cadmium,
chromium, cyanides, fluoride, lead, selenium,
and silver, sometimes contaminate water. Lead poses the
greatest threat to infants and young children with developing
nervous systems. It is possible that lead levels
in one home may be higher than levels at other homes
in the same community as a result of lead solder or
pipes used in the plumbing. Infants and children who
drink water with high levels of lead may experience delays
in their physical or mental development, showing
slight deficits in attention span and learning abilities.
Adults who drink this water over many years may develop
kidney problems or high blood pressure. If you
are concerned about a possibility of elevated lead levels
in a water supply, you should have the water tested
(municipal water utilities will usually do this for you).
Flushing the tap for 30 seconds to two minutes before
using the water will help the water supply stay fresh, but
wastes a lot of water. Don’t use hot water from the faucet
for drinking or cooking, especially when making baby
formula or other food for infants.
Arsenic occurs naturally in some water supplies. Arsenic
in water can cause symptoms such as dry, hacking
coughs and burning hands and feet, and increases the
risk of lung, skin, or bladder cancer. A federal study in
2000 of the water supply in Fallon, Nevada, showed that
customers were exposed to 90 parts per billion (ppb) of
arsenic, more than any other large system. This is almost
Agricultural Runoff Leaking Gas Tank
Agricultural Runoff
Well
Chemical Dump
Liquid Industrial Waste
Aquifer
Bedrock
Water
Table
Groundwater contamination.
twice the standard set in 1975, and nine times the
amount currently recommended by scientists and public
health doctors. Even if the community supply is
cleaned up, residents outside city limits rely on private
wells where the arsenic frequently reaches 700 ppb and
up to 2000 ppb.
Seepage of drainage from livestock manure can contaminate
shallow wells with nitrates, which in high
concentrations cause a condition commonly known as
“blue baby” disease in infants. Wells near homes treated
for termites may contain pesticides.
Chlorides from marine sediments, brine, seawater,
or industrial or domestic wastes can affect the taste of
groundwater. When copper enters the water supply from
natural deposits or from corrosion of copper piping, it
gives the water an undesirable taste.
Iron is frequently present in groundwater, or from
corroded iron pipes. Changes in water speed or direction
in local pipes can carry rust along. This can happen
when the valves are being repaired, the system is
being flushed or tested, or fire hydrants are in use. Iron
produces a red, brown, or yellow color in water, and can
cause brownish stains on washed clothes. Iron affects
the water’s taste, but it is not harmful to health.
Iron manganese is similar in color and taste to iron
and acts as a natural laxative. Sulfates from natural deposits
of Epsom salts or Glauber’s salts are also natural
laxatives. Zinc is derived from natural deposits. Zinc
does not pose a health threat but leaves an undesirable
taste.
Too much sodium in water may be dangerous for
people with heart, kidney, or circulatory problems who
need to observe low-sodium diets. Sodium can enter
water through salts used for ice on roads. Some water
softeners also increase sodium levels.
Biological Contaminants
Disease-producing organisms, such as bacteria, protozoa,
and viruses, are sometimes found in water. A positive
test for one particular kind of bacteria that is present
in the fecal wastes of humans and many animals
and birds—E. coli—indicates possible problems with
others. Coliform bacteria, including E. coli, outnumber
all other disease-producing organisms in water.
To avoid the growth of coliform bacteria, communities
choose water sources without much plant or animal
life, such as groundwater rather than surface water,
and try to keep human activity away from watersheds
(the areas that drain into the water supply) to protect
against contamination. Fertilizers and nutrient minerals
from farms and lawns can encourage bacterial growth.
Water stored in the dark and at low temperatures is less
likely to promote bacteria. When microorganisms do get
into the water supply, they are destroyed at water treatment
facilities.
Sometimes microorganisms do not pose a health
danger, but multiply and clog pipes and filters. They can
affect the water’s appearance, odor, and taste. Surface
water reservoirs may contain algae. Cooling towers can
also have high bacterial counts.
Radiological Characteristics
Radioactivity from mining and radioactive material used
in industry, power plants, and military installations can
contaminate water. Even low concentrations pose a danger
because radioactive contamination accumulates in
the body over time.
WATER TREATMENTS
It is best to prevent contamination of safe water supplies,
and conserve them for high-quality uses. When all
else fails, water is treated. Distillation, the process of
heating water to produce water vapor, is a simple, lowtech
way to eliminate pollution and purify water for
drinking, cooking, and laboratory use. Distilled water is
pure but has a flat taste.
The most important health-related water treatment
is disinfection to destroy microorganisms. It is required
for surface water, or for groundwater in contact with surface
water. Primary water treatment begins with filtration,
followed by disinfection to kill microorganisms
in the water. Secondary treatment keeps the level of disinfectant
high enough to prevent microorganism regrowth.
Disinfection is accomplished by a variety of
means, including chlorination, nanofiltration (filtration
for extremely small organisms), ultraviolet (UV) light,
bromine, iodine, ozone, and heat treatment.
Suspended particles and some materials affecting
color or taste can be removed by filtration. Filters can
also remove some bacteria, including Giardia cysts. The
water is passed through permeable fabric or porous beds
of filtering material.
Aeration, also called oxidation, improves taste and
color and helps to remove iron and manganese. Water
is sprayed or run down turbulent waterfalls to expose as
much of its surface to air as possible. Sculptural waterfalls
called flowforms, which have rhythmical, pulsating,
or figure-8 patterns, are both efficient and beautiful.
The retailer Real Goods in Hopland, California,
uses flowforms as part of a recycled water irrigation
system. Aeration improves the flat taste of distilled and
cistern water, and removes odors from hydrogen sulfide
and algae. Aeration may make the water more
corrosive.
The addition of fluoride to public water supplies
has greatly reduced the amount of childhood tooth decay.
Once we develop our adult teeth, we no longer benefit
from the fluoride, and too much fluoride can cause
yellow mottling on the teeth.
Water Distribution
pressure. Downfeed systems raise water to storage tanks
at the top of a building, from which it drops down to
plumbing fixtures. The rooftop storage tanks may have
to be heated to prevent freezing. The water in a rooftop
storage tank is also available for fire hoses. The heavy
tank requires extra structural support.
A water storage tank shares the uppermost zone in
most high-rise buildings with two-story elevator penthouses,
chimneys, plumbing vents, exhaust blowers, and
air-conditioning cooling towers. Solar collectors for hot
water heating are sometimes also on the roof. All of this
equipment is usually surrounded by a band or screen
two or more stories high.
SUPPLY PIPES
Lead was used for plumbing pipes by the Romans 2000
years ago, and the word “plumbing” is derived from the
Latin word for lead, “plumbum.” Lead pipes were used
through the 1950s. As a result, the U.S. Environmental
Protection Agency (EPA) is concerned even today that
lead may leach out of lead pipes and copper pipes joined
with lead solder and enter the water supply. Fortunately,
lead on the inside surface of a pipe quickly reacts with
sulfates, carbonates, and phosphates in the water to
form a coating that keeps it from leaching out of the
pipe. Experts believe, however, that the lead content in
water is likely to exceed safe guidelines when the water
is highly acidic or is allowed to sit in the lead pipes for
a long time.
Plumbing supply pipes are made of copper, red
brass, galvanized steel, and plastic. Galvanized steel pipe
was the standard for water supply until copper took over
in the 1960s. Steel pipe is strong and inexpensive, but
is subject to corrosion, and eventually rusts and springs
leaks. Steel pipes last from about 20 to 50 years. Mineral
deposits build up inside, reducing the inside diameter
and resulting in reduced water pressure at
faucets.
Red brass and copper tubing offer the best corrosion
resistance, with copper being less expensive, easier
to assemble, more resistant to acids, and lighter weight
than brass. Copper pipe lasts about twice as long as galvanized
pipe. However, it costs nearly twice as much by
length. Both flexible (soft temper) and rigid copper tubing
can be soldered, but only the flexible copper tubing
will accept compression fittings or flare fittings without
soldering.
Iron (ferrous) pipes and large brass pipes use
threaded connections. Copper pipes are joined with solder.
Solder, which was formerly made of lead, is now a
tin and antimony alloy. The molten solder is drawn into
the joint. This allows piping to be set up without turning
the parts to be connected, greatly facilitating installation.
It also permits pipes with thin walls, because no
threads have to be cut into their thickness. The smooth
interiors contribute less friction to flowing water.
Plastic pipe is lightweight, low-cost, corrosion resistant,
and easy to work with. It is available in flexible
form for outdoor use, and as rigid pipe. Plastic pipe is
made from synthetic resins derived from coal and petroleum.
Rigid polyvinyl chloride (PVC, white or gray)
and acrylonitrile-butadiene-styrene (ABS, black) pipes
are suitable for various cold-water applications. Both
ABS and PVC are thermoplastics, which can be molded
under heat. Because of their sensitivity to heat, however,
ABS and PVC are not used for hot water lines.
Chlorinated PVC (CPVC) pipe, which is usually
cream color, may be used for hot or cold water. It is a
thermoplastic and can be solvent welded, but it can be
used at higher temperatures than ABS or PVC. Polybutylene
(PB) pipe cannot be welded with solvent, and
uses compression fittings. It is flexible, and can be
snaked through walls. It is also less susceptible to damage
from freezing.
More access to plastic pipes must be supplied in
case fittings need to be repaired than where soldered
joints are used with metal pipes. Plastic pipe used for
potable water is required to have a seal from the National
Sanitation Foundation (NSF). Because plastic
pipes are shockproof, they are used in mobile homes
where vibration would be a problem for other types of
plumbing.
Engineers determine pipe sizes by the rate at which
the pipes will transport water when there is the most
demand. Pipes in the supply network tend to be smaller
as they get farther from the water source and closer to
the point of use, since not all of the water has to make
the whole trip. The sizes depend on the number and
types of fixtures to be served and pressure losses due to
friction and vertical travel. Water flowing through a
smaller pipe is under greater pressure than the same
amount of water in a larger pipe. Each type of fixture is
assigned a number of fixture units. Based on the total
number of fixture units for the building, the number of
gallons per minute (gpm) is estimated. The engineer assumes
that not all the fixtures are in use at the same
time, so the total demand is not directly proportional
to the number of fixture units. The interior designer
needs to give the engineer specific information about
the number of plumbing fixtures and their requirements
as early in the process as possible.
Pipes sweat when moisture in the air condenses on
the outsides of cold pipes. The condensation drops off
the pipes, wetting and damaging finished surfaces. Cold
water pipes should be insulated to prevent condensation.
Insulation also keeps heat from adjacent warm
spaces from warming the water in the pipes. When pipes
are wrapped in glass fiber 13 to 25 mm
with a tight vapor barrier on the exterior surface, the
moisture in the air can’t get to the cold surface. Hot
water pipes are insulated to prevent heat loss. When hot
and cold water pipes run parallel to each other, they
should be a minimum of 15 cm (6 in.) apart, so that
they don’t exchange heat.
In very cold climates, water pipes in exterior walls
and unheated buildings may freeze and rupture. Avoid
locating fixtures along exterior walls for this reason. If
water supply pipes must be located in an exterior wall,
they should be placed on the warm side (inside, in a
cold climate) of the wall insulation. A drainage faucet
located at a low point will allow the pipes to be drained
before being exposed to freezing weather.
SUPPLY LINES AND VALVES
From a branch supply line, a line runs out to each fixture
(Fig. 8-2). Roughing-in is the process of getting all
the pipes installed, capped, and pressure tested before
actual fixtures are installed. The rough-in dimensions for
Water Distribution
The design for the hair salon would involve a lot of
equipment. Right from the start, Harry made sure that
the engineers had spec sheets for all his client’s equipment.
There was just one problem. The client was looking
for a special shampoo sink for the project, and was
having trouble finding a supplier.
The engineer had to specify something so that the
building department could review and approve the
plans and the contractor could submit a bid. It was decided
to specify plumbing coming up into the cabinet
behind the sink, then out horizontally to the sink. The
drawings were prepared and sent to the contractor and
building department.
Meanwhile, the client found a supplier for the
shampoo sink. Once construction began, the contractor
needed the specifications on how the sink would be
plumbed. Despite repeated calls to the sink supplier,
Harry couldn’t get technical specs for the sink.
When the sinks arrived, the contractor discovered
that they were designed to be plumbed up the pedestal
from the floor below. The plumbing was already installed
in the cabinets behind the sink. It was possible
to modify the sink to accept pipes from behind, but they
would be exposed. Harry and the contractor decided to
bring the plumbing from behind through a cutout in
the pedestal. The exposed pipes were covered by a laminate
panel to match the cabinets, giving a finished appearance
and hiding the pipes.
each plumbing fixture should be verified with the fixture
manufacturer so that fixture supports can be built
in accurately during the proper phase of construction.
It is a good idea to have a shutoff valve to control
the flow of water at each vertical pipe (known as a riser),
with branches for kitchens and baths and at the runouts
to individual fixtures. Additional valves may be installed
to isolate one or more fixtures from the water supply
system for repair and maintenance. Compression-type
globe valves are used for faucets, drain valves, and hose
connections.
A dead-end upright branch of pipe located near a
fixture is called an air chamber. When a faucet is shut
off quickly, the water’s movement in the supply pipe
drops to zero almost instantly. Without the air chamber,
the pressure in the pipe momentarily becomes very
high, and produces a sound like banging the pipe with
a hammer—appropriately called water hammer—that
may damage the system. The air chamber absorbs the
shock and prevents water hammer.
Vacuum breakers keep dirty water from flowing
back into clean supply pipes. They also isolate water
from dishwashers, clothes washers, and boilers from the
water supply.
CHILLED WATER
Most public buildings provide chilled drinking water.
Previously, a central chiller with its own piping system
was used to distribute the cold water. More recently,
water is chilled in smaller water coolers at each point
of use, providing better quality at less cost. A pump constantly
circulates the chilled water, so you don’t have to
wait for the water to get cold. The chilled water piping
must be covered with insulation in a vapor-tight wrap
to avoid condensation.
Domestic hot water (DHW) is hot water that is used for
bathing, clothes washing, washing dishes, and many
other things, but not for heating building spaces. Domestic
hot water is sometimes called building service
hot water in nonresidential uses. Sometimes, when a
well-insulated building uses very little water for space
heating but uses a lot of hot water for other purposes,
a single large hot water heater supplies both.
HOT WATER TEMPERATURES
Excessively hot water temperatures can result in scalding.
People generally take showers at 41°C to 49°C
(105°F–120°F), often by blending hot water at 60°C
(140°F) with cold water with a mixing valve in the
shower. Most people experience temperatures above
43°C (110°F) as uncomfortably hot.
Some commercial uses require higher temperatures.
The minimum for a sanitizing rinse for a commercial
dishwasher or laundry is 82°C (180°F). Generalpurpose
cleaning and food preparation requires 60°C
(140°F) water. Temperatures above 60°C can cause serious
burns, and promote scaling if the water is hard.
However, high temperatures limit the growth of the
harmful bacterium Legionella pneumophila, which causes
Legionnaire’s disease. Water heaters for high temperature
uses have larger heating units, but the tanks can
be smaller because less cold water has to be mixed in.
Some appliances, such as dishwashers, heat water at the
point of use. Codes may regulate or limit high water
temperatures.
Lower temperatures are less likely to cause burns,
but may be inadequate for sanitation. Lower temperature
water loses less heat in storage and in pipes, saving
energy. Smaller heating units are adequate, but larger
storage tanks are needed. Solar or waste heat recovery
sources work better with lower temperature water
heaters. For energy conservation, use the lowest possible
temperatures.
WATER HEATERS
Water heating accounts for over 20 percent of the average
family’s annual heating bill. Hot water is commonly
heated using natural gas or electricity. It is also possible
to use heat that would be wasted from other systems,
or heat from steam, cogeneration, or wood-burning
systems.
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