§ 51-5. Types of protection.

The protective device required shall depend on the degree of hazard as tabulated below:

A. 

At the service connection to any premises where there is an auxiliary water supply handled in a separate piping system with no cross-connection, the public water supply shall be protected by an approved double check-valve assembly.

B. 

At the service connection on any premises on which there is an auxiliary water supply where cross-connections are known to exist or where it is unknown if cross-connections exist, the public water supply system shall be protected by an air-gap separation or an approved reduced pressure principle backflow prevention device.

C. 

At the service connection to any premises on which a substance that would be objectionable, but not hazardous to health if introduced into the public water supply, is handled so as to constitute a cross-connection, the public water supply shall be protected by an approved double check-valve assembly.

D. 

At the service connection to any premises on which a substance of unusual toxic concentration or danger to health is or may be handled, but not under pressure, the public water supply shall be protected by an air-gap separation or an approved reduced pressure principle backflow prevention device. This device shall be located as close as practicable to the water meter, and all piping between the water meter and receiving tanks shall be entirely visible.

E. 

At the service connection to any premises on which any material dangerous to health or any toxic substance in toxic concentration is or may be handled under pressure, the public water supply shall be protected by an air-gap separation. The air gap shall be located as close as practicable to the water meter, and all piping between the water meter and receiving tanks shall be entirely visible. If these conditions cannot be reasonably met, the public water supply shall be protected with an approved reduced pressure principle backflow prevention device, provided that the alternative is acceptable to the water purveyor.

F. 

At the service connection to any sewage treatment plant or sewage pumping station, the public water supply shall be protected by an air-gap separation. The air gap shall be located as close as practicable to the water meter, and all piping between the water meter and receiving tanks shall be entirely visible. If these conditions cannot be reasonably met, the public water supply shall be protected with an approved reduced pressure principle backflow prevention device.

G. 

At the service connection to any premises not covered by Subsections A through F above, the public water supply shall be protected with an approved single check-valve assembly.