Plumbing may be defined as
practice, materials, and
fixtures used in the
installation, maintenance,
and alteration of all
piping, fixtures,
appliances, and
appurtenances in connection
with sanitary or storm
drainage facilities, the
venting system, and the
public or private water
supply systems. Plumbing
does not include the trade
of drilling water wells,
installing water softening
equipment, or the business
of manufacturing or selling
plumbing fixtures,
appliances, equipment, or
hardware. A plumbing system
consists of three separate
parts: an adequate potable
water supply system, a safe,
adequate drainage system and
ample fixtures and
equipment.
Background Factors
The generalized inspection
of a home is concerned with
a safe water supply system,
an adequate drainage system,
and ample and proper
fixtures and equipment. This
explains features of a
residential plumbing system
and the basic plumbing terms
the inspector must know and
understand to identify
properly housing code
violations involving
plumbing and the more
complicated defects that he
will refer to the
appropriate agencies.
Definitions
Air Chambers
Pressure absorbing devices
that eliminate water hammer.
They should be installed as
close as possible to the
valves or faucet and at the
end of long runs of pipe.
Air Gap (Drainage
System)
The unobstructed vertical
distance through the free
atmosphere between the
outlet of a water pipe and
the flood level rim of the
receptacle into which it is
discharging.
Air Gap (Water
Distribution System)
The unobstructed vertical
distance through the free
atmosphere between the
lowest opening from any pipe
or faucet supplying water to
a tank, plumbing fixture, or
other device and the flood
level rim of the receptacle.
Air Lock
An air lock is a bubble of
air which restricts the flow
of water in a pipe.
Backflow
The flow of water or other
liquids, mixtures, or
substances into the
distributing pipes of a
potable water supply from
any source or sources other
than the intended source.
Back siphonage is one type
of backflow.
Back Siphonage
The flowing back of used,
contaminated, or polluted
water from a plumbing
fixture or vessel into a
potable water supply due to
a negative pressure in the
pipe.
Branch
Any part of the piping
system other than the main,
riser, or stack.
Branch Vent
A vent connecting one or
more individual vents with a
vent stack.
Building Drain
The part of the lowest
piping of a drainage system
that receives the discharge
from soil, waste, or other
drainage pipes inside the
walls of the building
(house) and conveys it to
the building sewer beginning
3 feet outside the building
wall.
Cross Connection
Any physical connection or
arrangement between two
otherwise separate piping
systems, one of which
contains potable water and
the other either water of
unknown or questionable
safety or steam, gas, or
chemical whereby there may
be a flow from one system to
the other, the direction of
flow depending on the
pressure differential
between the two systems.
(See Backflow and Back
siphonage.)
Disposal Field
An area containing a series
of one or more trenches
lined with coarse aggregate
and conveying the effluent
from the septic tank through
vitrified clay Pine or
perforated, non-metallic
pipe, laid in such a manner
that the flow will be
distributed with reasonable
uniformity into natural
soil.
Drain
Any pipe that carries waste
water or water-borne waste
in a building (house)
drainage system.
Flood Level Rim
The top edge of a receptacle
from which water overflows.
Flushometer Valve
A device that discharges a
predetermined quantity of
water to fixtures for
flushing purposes and is
closed by direct water
pressures.
Flush Valve
A device located at the
bottom of the tank for
flushing water closets and
similar fixtures.
Grease Trap
See Interceptor.
Hot Water
Potable water that is heated
to at least 120°F and used
for cooking, cleaning,
washing dishes, and bathing.
Insanitary
Contrary to sanitary
principles injurious to
health.
Interceptor
A device designed and
installed so as to separate
and retain deleterious,
hazardous, or undesirable
matter from normal wastes
and permit normal sewage or
liquid wastes to discharge
into the drainage system by
gravity.
Leader
An exterior drainage pipe
for conveying storm water
from roof or gutter drains
to the building storm drain,
combined building sewer, or
other means of disposal.
Main Vent
The principal artery of the
venting system, to which
vent branches may be
connected.
Main Sewer
See Public Sewer.
Pneumatic
The word pertains to devices
making use of compressed air
as in pressure tanks boosted
by pumps.
Potable Water
Water having no impurities
present in amounts
sufficient to cause disease
or harmful physiological
effects and conforming in
its bacteriological and
chemical quality to the
requirements of the Public
Health Service drinking
water standards or meeting
the regulations of the
public health authority
having jurisdiction.
P & T (Pressure and
Temperature) Relief Valve
A safety valve installed on
a hot water storage tank to
limit temperature and
pressure of the water.
P Trap
A trap with a vertical inlet
and a horizontal outlet.
Public Sewer
A common sewer directly
controlled by public
authority.
Relief Vent
An auxiliary vent that
permits additional
circulation of air in or
between drainage and vent
systems.
Septic Tank
A watertight receptacle that
receives the discharge of a
building's sanitary drain
system or part thereof and
is designed and constructed
so as to separate solid from
the liquid, digest organic
matter through a period of
detention, and allow the
liquids to discharge into
the soil outside of the tank
through a system of
open-joint or perforated
piping, or through a seepage
pit.
Sewerage System
A sewerage system comprises
all piping, appurtenances,
and treatment facilities
used for the collection and
disposal of sewage, except
plumbing inside and in
connection with buildings
served and the building
drain.
Soil Pipe
The pipe that directs the
sewage of a house to the
receiving sewer, building
drain, or building sewer.
Soil Stack
The vertical piping that
terminates in a roof vent
and carries off the vapors
of a plumbing system.
Stack Vent
An extension of a solid or
waste stack above the
highest horizontal drain
connected to the stack.
Sometimes called a waste
vent or a soil vent.
Storm Sewer
A sewer used for conveying
rain water, surface water,
condensate. cooling water,
or similar liquid waste.
Trap
A trap is a fitting or
device that provides a
liquid seal to prevent the
emission of sewer gases
without materially affecting
the flow of sewage or waste
water through it.
Vacuum Breaker
A device to prevent backflow
(back siphonage) by means of
an opening through which air
may be drawn to relieve
negative pressure (vacuum).
Vent Stack
The vertical vent pipe
installed to provide air
circulation to and from the
drainage system and that
extends through one or more
stories.
Water Hammer
The loud thump of water in a
pipe when a valve or faucet
is suddenly closed.
Water Service Pipe
The pipe from the water main
or other sources of potable
water supply to the
water-distributing system of
the building served.
Water Supply System
The water supply system
consists of the water
service pipe, the
water-distributing pipes,
the necessary connecting
pipes, fittings, control
valves, and all
appurtenances in or adjacent
to the building or premises.
Wet Vent
A vent that receives the
discharge of waste other
than from water closets.
Yoke Vent
A pipe connecting upward
from a soil or waste stack
to a vent stack for the
purpose of preventing
pressure changes in the
stacks.
Main Features of an
Indoor Plumbing System
The primary functions of the
plumbing system within the
house are as follows:
-
To bring an adequate and
potable supply of hot
and cold water to the
users of the dwelling.
- To
drain all waste water
and sewage discharged
from these fixtures into
the public sewer, or
private disposal system.
It is, therefore, very
important that the housing
inspector familiarize
himself fully with all
elements of these systems so
that he may recognize
inadequacies of the
structure's plumbing as well
as other code violations.
Elements of a
Plumbing System
Water Service:
The piping of a house
service line should be as
short as possible. Elbows
and bends should be kept to
a minimum since these reduce
the pressure and therefore
the supply of water to
fixtures in the house. The
house service line should
also be protected from
freezing. The burying of the
line under 4 feet of soil is
a commonly accepted depth to
prevent freezing. This depth
varies, however, across the
country from north to south.
The local or state plumbing
code should be consulted for
the recommended depth in
your area of the country.
The materials used for a
house service may be copper,
cast iron, steel or wrought
iron. The connections used
should be compatible with
the type of pipe used.
-
Corporation stop - The
corporation stop is
connected to the water
main. This connection is
usually made of brass
and can be connected to
the main by use of a
special tool without
shutting off the
municipal supply. The
valve incorporated in
the corporation stop
permits the pressure to
be maintained in the
main while the service
to the building is
completed.
-
Curb
stop - The curb stop is
a similar valve used to
isolate the building
from the main for
repairs, nonpayment of
water bills, or flooded
basements. Since the
corporation stop is
usually under the street
and would necessitate
breaking the pavement to
reach the valve, the
curb stop is used as the
isolation valve.
-
Curb
stop box - The curb stop
box is an access box to
the curb stop for
opening and closing the
valve. A long-handled
wrench is used to reach
the valve.
-
Meter
stop -The meter stop is
a valve placed on the
street side of the water
meter to isolate the
meter for installation
or maintenance. Many
codes require a gate
valve on the house side
of the meter to shut off
water for house plumbing
repairs. The curb and
meter stops are not to
be used frequently and
can be ruined in a short
time if used very
frequently.
-
Water
meter - The water meter
is a device used to
measure the amount of
water used in the house.
It is usually the
property of the city and
is a very delicate
instrument that should
not be abused. Since
the electric system is
usually grounded to the
water line, a grounding
loop-device should be
installed around the
meter. Many meters come
with a yoke that
maintains electrical
continuity even though
the meter is removed.
Hot and Cold Water
Main Lines: The hot
and cold water main lines
are usually hung from the
basement ceiling and are
attached to the water meter
and hot-water tank on one
side and the fixture supply
risers on the other. These
pipes should be installed in
a neat manner and should be
supported by pipe hangers or
straps of sufficient
strength and number to
prevent sagging. Hot and
cold water lines should be
approximately 6 inches apart
unless the hot water line is
insulated. This is to insure
that the cold water line
does not pick up heat from
the hot water line. The
supply mains should have a
drain valve or stop and
waste valve in order to
remove water from the system
for repairs. These valves
should be on the low end of
the line or on the end of
each fixture riser.
The fixture risers start at
the basement main and rise
vertically to the fixtures
on the upper floors. In a
one-family dwelling, riser
branches will usually
proceed from the main riser
to each fixture grouping. In
any event the fixture risers
should not depend on the
branch risers for support
but should be supported with
a pipe bracket.
Each fixture is then
connected to the branch
riser by a separate line.
The last fixture on a line
is usually connected
directly to the branch
riser.
Hot Water Heaters:
Hot water heaters are
usually powered by
electricity, fuel oil, gas,
or in rare cases, coal or
wood. They consist of a
space for heating the water
and a storage tank for
providing hot water over a
limited period of time. All
hot water heaters should be
fitted with a
temperature-pressure relief
valve no matter what fuel is
used. This valve will
operate when either the
temperature or the pressure
becomes too high due to an
interruption of the water
supply or a faulty
thermostat.
Pipe Sizes:
The size of basement mains
and risers depends on the
number of fixtures supplied.
However, a 3/4 inch pipe is
usually the minimum size
used. This allows for
deposits on the pipe due to
hardness in the water and
will usually give
satisfactory volume and
pressure.
Drainage System
The water supply brought
into the house and used is
discharged through the
drainage system. This system
is either a sanitary
drainage system carrying
just interior waste water or
a combined system carrying
interior waste and roof
runoff.
Sanitary Drainage
System: The proper
sizing of the sanitary drain
or house drain depends on
the number of fixtures it
serves. The usual minimum
size is 6 inches in dial
diameter. The materials used
are usually cast iron,
vitrified clay, plastic, and
in rare cases, lead. For
proper flow in the drain the
pipe should be sized so that
it flows approximately
one-half full. This ensures
proper scouring action so
that the solids contained in
the waste will not be
deposited in the pipe.
-
Sizing of house drain -
The Uniform Plumbing
Code Committee has
developed a method of
sizing of house drains
in terms of "fixture
units." One ''fixture
unit" equals
approximately 71 D2
gallons of water per
minute. This is the
surge flow-rate of water
discharged from a wash
basin in 1 minute. All
other fixtures have been
related to this unit.
Sanitary Drain Sizes
-
Grade of house drain - A
house drain or building
sewer should be sloped
toward the sewer to
ensure scouring of the
drain. The usual pitch
of a house or building
sewer is 1 D4 inch fall
in 1 foot of length.
-
Fixture and branch
drains - A branch drain
is a waste pipe that
collects the waste from
two or more fixtures and
conveys it to the
building or house sewer.
It is sized in the same
way as the house sewer,
taking into account that
all water closets must
have a minimum 3-inch
diameter drain, and only
two water closets may
connect into one 3-inch
drain.
All branch drains must join
the house drain with a "Y"
-type fitting. The same is
true for fixture drains
joining branch drains. The
"Y" fitting is used to
eliminate, as much as
possible, the deposit of
solids in or near the
connection. A build-up of
these solids will cause a
blockage in the drain.
-
Traps - A plumbing trap
is a device used in a
waste system to prevent
the passage of sewer gas
into the structure and
yet not hinder the
fixture's discharge to
any great extent. All
fixtures connected to a
household plumbing
system should have a
trap installed in the
line.
The effect of sewer gases on
the human body are known;
many are extremely harmful.
Additionally, certain sewer
gases are explosive. A trap
will prevent these gases
from passing into the
structure. The depth of the
seal in a trap is usually 2
inches. A deep seal trap has
a 4-inch seal.
The purpose of a trap is to
seal out sewer gases from
the structure. Since a
plumbing system is subject
to wide variations in flow,
and this flow originates in
many different sections of
the system, there is a wide
variation in pressures in
the waste lines. These
pressure differences tend to
destroy the water seal in
the trap. To counteract this
problem mechanical traps
were introduced. It has been
found, however, that the
corrosive liquids flowing in
the system corrode or jam
these mechanical traps. It
is for this reason that most
plumbing codes prohibit
mechanical traps.
There are many manufacturers
of traps, and all have
varied the design somewhat.
The "P" trap is usually
found in lavatories, sinks,
urinals, drinking fountains,
showers, and other
installations that do not
discharge a great deal of
water.
Drum trap
The drum trap is another
water seal-type trap. They
are usually used in the
4x5-inch or 4x8-inch sizes.
These traps have a greater
sealing capacity than the
"P" trap and pass large
amounts of water quickly.
Drum traps are commonly
connected to bathtubs, foot
baths, sitz baths, and
modified shower baths.
Objectionable traps
The "S" 1 and the 3h "S"
trap should not be us in
plumbing installations. They
are almost impossible to
ventilate properly, and the
3h "S" trap forms a perfect
siphon.
The bag trap, an extreme
form of "S" trap, is seldom
found.
Any trap that depends on a
moving part for its
effectiveness is usually
inadequate and has been
prohibited by the local
plumbing codes. These traps
work, but their design
usually results in their
being higher priced than the
"P" or drum traps. It should
be remembered that traps are
used only to prevent the
escape of sewer gas into the
structure. They do not
compensate for pressure
variations. Only proper
venting will eliminate
pressure problems.
Ventilation
A plumbing system is
ventilated to prevent trap
seal loss, material
deterioration. and flow
retardation.
Trap seal loss
The seal in a plumbing trap
may be lost due to siphonage
(direct and indirect or
momentum), back pressure,
evaporation, capillary
attraction, or wind effect.
The first two named are
probably the most common
causes of loss. If a waste
pipe is placed vertically
after the fixture trap, as
in an "S" trap, the waste
water continues to flow
after the fixture is emptied
and clears the trap. This is
caused by the pressure of
air on the fixture water's
being greater than the
pressure of air in the waste
pipe. The action of the
water discharging into the
waste pipe removes the air
from that pipe and thereby
causes a negative pressure
in the waste line. In the
case of indirect or momentum
siphonage, the flow of water
past the entrance to a
fixture drain in the waste
pipe removes air from the
fixture drain. This reduces
the air pressure in the
fixture drain, and the
entire assembly acts as an
aspirator such as the
physician uses to spray an
infected throat.
Back pressure
The flow of water in a soil
pipe varies according to the
fixtures being used. A
lavatory gives a small flow
and a water closet a large
flow. Small flows tend to
cling to the sides of the
pipe, but large ones form a
slug of waste as they drop.
As this slug of water falls
down the pipe the air in
front of it becomes
pressurized. As the pressure
builds it seeks an escape
point. This point is either
a vent or a fixture outlet.
If the vent is plugged or
there is no vent, the only
escape for this air is the
fixture outlet. The air
pressure forces the trap
seal up the pipe into the
fixture. If the pressure is
great enough the seal is
blown out of the fixture
entirely. Figures 6-17 and
6-18 illustrate this type of
problem.
Vent sizing
Vent pipe installation is
similar to that of soil and
waste pipe. The same fixture
unit criteria are used. Vent
pipes of less than 11 D4
inches in diameter should
not be used. Vents smaller
than this diameter tend to
clog and do not perform
their function.
-
Individual fixture
ventilation -
This type of
ventilation is generally
used for sinks, lavatories,
drinking fountains, and so
forth
-
Unit venting -
The unit
venting system is commonly
used in apartment buildings.
This type of system saves a
great deal of money and
space when fixtures are
placed back to back in
separate apartments.
-
Wet venting -
Wet venting
of a plumbing system is
common in household bathroom
fixture grouping. It is
exactly what the name
implies: the vent pipe is
used as a waste line.
Total drainage system
Up to now we have talked
about the drain, soil waste,
and vent systems of a
plumbing system separately.
For a working system,
however, they must all be
connected.
cell
850-319-3888 
