(3) Provide for access to the tank for maintenance, but prevent removal of
the cover by a suitable locking device.
(4) Monitor the quality of the spring water with periodic checks for
contamination. A marked increase in turbidity after a storm is a good indication that
surface runoff is reaching the spring.
Section II. CROSS CONNECTIONS IN WATER DISTRIBUTION SYSTEMS
Public health officials have long been concerned about cross connections and
backflow connections in plumbing systems and in public drinking water distribution
systems. Such cross connections, which make possible the contamination of potable
water, are ever-present dangers. An example of what can happen is the epidemic of
amebic dysentery that occurred in Chicago in 1933 when old, defective, and improperly
designed plumbing and plumbing fixtures permitted the contamination of drinking water.
As a result, 1,409 people contracted amebic dysentery--of which, 98 subsequently died.
This epidemic and similar others have made clear the responsibiIity of all persons
involved in public water supplies, distribution, and plumbing for recognizing and
eliminating cross connections.
a. Cross Connection. A cross connection is any physical connection, whether
permanent or temporary, between a potable water system and a nonpotable system or
source. Cross connections may be further defined as direct or indirect.
(1) A direct cross connection is a solid pipe connection between a potable
and nonpotable system.
(2) An indirect cross connection is one in which there is not a continuous
connection at all times, but which can create such a connection when certain conditions
exist. An example would be a leaking water Iine and a leaking sewer Iine laid in the
same trench and in the presence of a pressure differential which would permit
wastewater to enter the potable water line.
b. Backflow. Backflow is any flow of nonpotable water or other liquid into a
potable water system.
c. Backsiphonage. Backsiphonage is backflow caused by negative pressure in
the potable water system at the point of occurrence.