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Caution:
Please read our safety
information before attempting any testing, maintenance
or repairs.
The plumbing fixtures in your home are connected
by two basic systems: water supply and drainage.
The water supply consists of an incoming cold
water main, which splits off to the hot water heater and to each
of the cold water taps. The hot water main begins at the water
heater and branches off to each of the hot water taps. Supply
lines can be steel, copper or plastic and are commonly range from
1 inch down to 1/2 inch. The water supply is under pressure, precisely
what pressure varies by the water source (municipal supply, well,
cistern) but 40-50 psi (pounds per square inch) is considered
good. Too high of pressure, generally 80 psi or higher, can result
in damage to fixtures, appliances and pipes. Too low of pressure
results in weak flow at the tap and is simply inconvenient. Pressure
boosters can be used to increase water pressure and regulators
can be used to reduce pressure.
The drainage system is referred to as the DWV
system for drain, waste and vent. DWV pipe can be iron, steel
or plastic and typically ranges in size from 1 1/2 inches up to
4 inches or more. Most new installations use plastic pipe. The
DWV system differs from the supply in that it is not under pressure.
Waste water travels simply by gravity. The waste lines in your
home are carefully arranged to allow for a downward slope all
the way out to your sewer or septic system. In cases where a continuous
slope is impossible or waste water must travel uphill, pumps are
employed to move the waste water.
Each fixture in your home has a device called
a trap. It is designed to trap a small amount of water in it after
each use of the fixture. Your toilet has a trap that is visible
because you can actually see the water in the bowl. A trap is
simply a "U" shaped section in which water can pass
through, but some always remains behind. By leaving enough water
to completely fill the trap, sewer gas carrying unpleasant odors
cannot enter your home. The water also deters rodents and insects
from traveling through the pipe and into your home.
Another part of the DWV system is the vent system.
If there were no vents on the waste system, a variety of problems
would occur. The most basic problem is that as the water flows
down, a suction would be created behind the water. That suction
would then siphon the water out the traps in the fixtures and
allow sewer gas to flow into your home.
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