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Waterproofing and Window Wells | >>Water
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Drain, Backfill and Rough Grade | Basement
lateral is the pipe that runs from the city water
supply into the house. The sewer lateral is the pipe
that runs from the house to the city sewer pipe or
to the septic tank
The supply pipe must be
able to withstand high pressure and corrosion, both
internally and externally. Flexible copper is probably
the most common type of water lateral although plastic
is used also. The water lateral is placed in a trench
from the city water pipe to the house and is placed
below the frost line to prevent freezing.
Modern Sewer lateral is
pipe is made from plastic pipe, either ABS or PVC.
Traditionally sewer lateral was made from clay, cast
iron, concrete, or tar fiber pipe.
For the sewer lateral
, the pipe is placed in a trench dug with a shelf
to one side (see illustration below). The pipe is
hooked to the house sewer main and runs downhill to
the city sewer main. The sewer lateral is installed
with a "T" connection right before it hooks
to the city pipe (this is used to plug the pipe for
testing). As the pipe leaves the house a "Y"
fitting and vertical pipe installed for a cleanout.
The sewer lateral is then filled with water to check
for leaks and the test plug is pulled to make sure
that it drains properly. The pipe is then covered
with sand or pea gravel to protect it from breakage.
The water lateral hooks
to the water supply and runs to the house. Before
it actually goes into the house it runs through the
water meter. In some areas there may not even be a
water meter, or the water meter may be installed inside
The installer drills a hole through the foundation
( or runs the supply under the footing into the basement
or crawlspace portion of the house. A main shutoff
valve is installed inside the house. In some areas
the main shut off valve may be installed outside the
house and accessible through a vertical pipe in the
yard. The Yoke that holds the water meter usually
has a shut off valve. The water lateral is pressurized
or fill with water to test for leaks. After testing
it is covered with sand or pea grave for protection.
Typically the water
and sewer laterals are installed by excavators or
plumbers. A sewer cleanout is installed next to the
house on the exterior. The cleanout is a "Y"
fitting that is attached to the main line to allow
the line to be unblocked. Check with the city water
and sewer dept about the location of the cleanout.
The water supply is also installed at the same time
as the sewer lateral. A trench is dug for the sewer
and the water lateral is placed above the sewer on
Savings can be made
by placing both laterals in the same trench. It is
common practice and saves money to schedule the laterals
as part of the backfilling process if the same subcontractor
is doing both the excavation and laterals.
The lateral inspection will vary depending on where
you live. In some areas the building department will
inspect, and in others the water utilities will be
in charge. Some jurisdictions require that the water
and sewer are water tested, and others don't. Most
of the time, installers know the local codes and procedures
for inspections. Contact your local building department
and water utilities for local requirements.