source also lends itself readily to the purification
equipment common to most engineer units. Sur-
face water is the most easily developed source of
water. Methods of constructing intake points for
land surface water sources are discussed below.
If the stream is not too swift and the water
is sufficiently deep, an intake may be prepared
quickly by placing the intake strainer on a rock.
This will prevent clogging of the strainer by the
streambed and provide enough water overhead to
prevent the suction of air into the intake pipe. If
the water source is a small stream or shallow lake,
Figure 9-5.Direct intake with hose on bottom of water
the intake pipe can be secured to a post or pile
as shown in figure 9-5.
When a stream is so shallow that the intake
screen is not covered by at least 4 inches of water,
a pit should be dug and the screen laid on a rock
or board placed at the bottom of the pit. Pits dug
in streams with clay or silt bottoms should be lined
with gravel to prevent dirt from entering the
purification equipment (fig. 9-6). The screen is
surrounded by gravel to prevent collapse of the
sides of the pit and also shield the screen from
damage by large floating objects. The gravel also
acts as a coarse strainer for the water. A similar
method may be provided by enclosing the intake
screen in a bucket as shown in figure 9-7.
The level of the water in small streams can be
raised to cover the intake strainer by building a
In swiftly flowing streams, a wing or baffle
dam can be built to protect the intake screen
without impounding the water.
Floats made of logs, lumber, sealed cans, or
empty fuel drums can be used to support the in-
take strainer in deep water. Floats are especially
useful in large streams where the quality of the
water varies across its width or where the water
is not deep enough near the banks to cover the
intake strainer. The intake point can be covered
by an adequate depth of water by anchoring or
stationing the float at the deep part of the stream.
The intake hose should be secured to the top of
the float, allowing enough slack for movement
Figure 9-6.Surface intake with hose buried in gravel-filled pit.