A. 
The following are recommendations for the protection of water supplies and fixtures against contamination through interconnections and unprotected waste lines:
(1) 
Aspirator and filter pumps: Use siphon preventer valves on waterlines to fixtures.
(2) 
Baths.
(a) 
Tub, sitz and foot: Use over-rim inlets discharging above the flood lines.
(b) 
Continuous flow: Use air inlet valves on waterlines to fixtures.
(3) 
Bedpan washers: Use venturi air breaks on waterlines between control valves and fixtures.
(4) 
Bidets: Use siphon preventer check valves or air inlet valves on waterlines to fixtures.
(5) 
Dental cuspidors: Use siphon preventer check valves on waterlines to fixtures.
(6) 
Drinking fountains: Use fixtures complying with the recommendations of the American Public Health Association.
(7) 
Floor drains - flush rim: Avoid use where possible. When used, provide venturi air break air inlet valves or siphon preventer check valves on waterlines to fixtures.
(8) 
Kitchen and pantry fixtures: Use fixtures having inlets discharging above floor lines or provide breaks on waterlines to fixtures. Provide air breaks on all waste connections.
(9) 
Laundry trays: Use fixtures with over-rim inlets discharging above flood lines.
(10) 
Laundry washing machines: Use air breaks or air vents or air inlet valves on waterlines to submerged inlets. Use air breaks on all waste connections.
(11) 
Lavatories: Use fixtures with over-rim inlets discharging above flood lines.
(12) 
Photo developing tanks: Use air breaks on waterlines to fixtures.
(13) 
Pump primers: Use air breaks on priming lines to pumps.
(14) 
Sinks.
(a) 
Slop: Use fixtures with over-rim inlets discharging above flood lines.
(b) 
Flush rim: Use siphon preventer check valves or air inlet valves on waterlines to rim.
(15) 
Spray heads, movable: Use siphon preventer check valves or air inlet valves on waterlines to fixtures.
(16) 
Sterilizers: Use leak protected valve and air breaks on waterlines to fixtures. Use air breaks on all waste lines.
(17) 
Urinals with flush valves: Use siphon preventer check valves on waterlines to flush valves.
(18) 
Water closets, flush valve: Use siphon preventer check valves on waterlines to flush valves.
(19) 
Water distribution systems: Use elevated tanks or air relief valves on cold-water risers. Connect laterals to risers above the top of the fixtures served by laterals.
B. 
Whenever possible, existing fixtures should be provided with venturi air breaks between the water supply valves and fixtures. Where this is not possible because of fixture design, siphon preventer check valves should be used.
C. 
Air relief valves on risers are not considered necessary in ordinary residential or small institutional installations.