How Water Works
Illustrated processes, equ ipment, and technology
Surface Water Sources:
Multiple Inlet Ports Offer Water Quality Options
1
W
ater is removed from a surface
impoundment or river by an intake
structure. Simple intakes are submerged
screened pipes, some of which can be
moved to withdraw water from various
points. Shown here is an intake structure with multiple
inlet ports. A screened port can be opened while the others
are closed to allow water to be drawn from the freshest part of
the reservoir or to compensate for changing water conditions,
elevation, or ice cover.
1. Inlet valve actuators are used to open and close the
appropriate ports.
ports
6
2a
5a
3
8
2a, 2b, and 2c. Screened intake ports are closed by slide gates when not in use.
5b
3. Water flows into the wet well from the open gate.
4. The raw water transmission main carries the water from the wet well to the water treatment plant.
plant
5a, 5b, and 5c. The epilimnion (5a) is the top water layer, and the shallowest and warmest. The water density barriers
created by the temperature gradient in the metalimnion (5b) prevent mixing with the lowest layer, the hypolimnion (5c).
7
2b
6. Reservoir circulators and aerators can help prevent thermal stratification. Shown here is a solar-powered circulator
that can operate 24/7 on energy stored in a battery.
7. Dams are classified by type of construction material and how they resist the pressure forces
imposed on them. Here a concrete arch dam resists movement by transferring the thrust
of the water to the rock walls of the canyon.
5c
2c
4
8. The grate in the dam can be adjusted to
control flows into the river below.
Illustration elements exaggerated for emphasis.
18 Opflow August 2006
2006 © American Water Works Association
www.awwa.org/communications/opflow
www.awwa.org/communications/opflow 2006 © American Water Works Association
August 2006 Opflow 19