Page 492 - 2018 National Home Improvement

2018 National Home Improvement Estimator, All Rights Reserved Page 393

Water Supply
Low water pressure is usually due to an accumulation of lime or corrosion in supply lines, though it may
also be that supply lines are too small. Main distribution pipes should be 3/4” inside diameter. Branch
lines serving a single fixture may be 1/2” inside diameter.

If the house is served by a well on the premises, check the gauge on the pressure tank. A good
operating pressure is 40 or 50 psi. If pressure is less than 20 psi, the pump isn’t operating properly or
the pressure setting is too low.

Checking Pipe Sizes
The nominal (name) size of pipe refers to the inside diameter.

Copper pipe:
1/2" inside diameter pipe has 5/8” outside diameter
3/4" inside diameter pipe has 7/8” outside diameter

Galvanized pipe:
1/2" inside diameter pipe has 7/8” outside diameter
3/4" inside diameter pipe has 1-1/8” outside diameter.

Water Hammer
Water hammer is a loud banging noise in supply lines caused when water is shut off abruptly. Over a
period of time, water hammer can seriously damage valves and fixtures throughout the supply system.
An air chamber placed on a supply line can absorb enough shock to prevent water hammer. If there’s
already an air chamber on the line, the air may have escaped. A waterlogged air chamber offers no
protection against water hammer. To restore air to the chamber, turn off the water at the source. Open
the air chamber to drain out any excess water, then reseal the chamber and restore the water pressure.

Plumbing Drain, Waste and Vent Lines
The drainage system consists of sewer laterals, drainage pipes and vents. It’s common for pipes in
older homes to break or become clogged. Most older homes have cast iron drain lines, which rust out
after about 70 years. In some cases, the pipe diameter will be less than required by current codes. This
is especially true for vent piping.

Sewer drain pipe in older homes may be bell-joint vitreous tile. Joints can break under pressure as the
soil settles or heaves, and a broken pipe is an invitation for tree roots. Even if pipes aren’t broken, tree
roots can enter through the pipe joints and obstruct the flow of sewage. When this happens, remove the
roots with a power-driven snake. If the system has to be snaked out every few months, you can assume
there’s a break or an open joint somewhere that needs repair. Tile or steel drainage pipe should last as
long as the house. But these lines can accumulate sediment and need flushing out occasionally.

If you notice the smell of sewer gas, a vent stack is probably obstructed. The vent stacks you see
running through the roof are designed to equalize air pressure in the drainage system. If a vent is
obstructed, waste flowing through the system can create a vacuum that sucks water out of fixture traps,
allowing sewer gas to enter the home. All fixtures should drain by gravity, not through suction. If you
notice that water is being sucked out of the trap when a toilet is flushed, you can assume the roof vent
is obstructed.