Purification of Water Supplies

All water delivered by a private system for human consumption is expected to meet or exceed the latest revisions of the drinking water standards published by the U.S. Public Health Service. Water from such systems should be tested for indication of sewage pollution at least as frequently as is recommended by local health authorities. Such tests should be conducted as prescribed by the current edition of "Standard Methods for the Examination of Water and Sewage," as published by the American Public Health Association and American Water Works Association.

Because of the limited number of samples collected from a private water supply, the presence of coliform bacteria in any one properly collected sample would classify the water as unsatisfactory for human consumption unless proper treatment is supplied.

When tests show evidence of sewage pollution, suitable treatment equipment shall be installed. This equipment must be capable of destroying or removing pathogen contaminants in the water under the conditions inherent in the water system. It shall be such that positive evidence of adequate treatment can be demonstrated by a residual test practical for the user of the water system. The equipment should be dependable and positive, and require a minimum of attention. It is desirable to provide bactericidal potential through all parts of they system following the treatment point.

Water systems on supplies which show evidence of contamination should be designed to provide the combination of residual and retention time necessary for destroying harmful bacteria.

There are thousands of types of non-pathogenic organisms which may be present in a water supply. They may cause slimes and growths that will clog pipes, pumps and valves and reduce water flow, produce tastes and odors and harbor pathogenic bacteria. Where they are present, chlorination equipment or other suitable treatment equipment should be provided.

Iron – If iron in excess of 0.3 ppm is present in a water supply, suitable equipment for removing or sequestering the iron should be installed. This equipment may employ the techniques of chemical oxidation followed by filtration, iron exchange, chemical sequestration or other proven techniques consistent with the chemical and physical properties of the raw water.

Manganese – If manganese is present in a water supply in excess of 0.5 ppm, removal process similar to that required for iron should be installed.

Hydrogen Sulfide – If the concentration of hydrogen sulfide in the water supply is such as to be offensive, adequate removal equipment should be installed. This equipment may employ oxidation by chlorination or other proven techniques.

Hardness – Where hardness is present in excess of five grains per gallon, or where lower levels of hardness are preferred, equipment conforming to the current edition of Water Conditioning Foundation Standard S-100 should be installed.

Other undesirable dissolved materials, when they occur in concentrations higher than those established by the latest revision of the USPHS drinking water standards, should be removed by suitable treatment processes.

Where low pH contributes to corrosion, equipment to adjust pH or to inject a corrosion inhibitor (such as a polyphosphate, a silicate or soda ash) should be provided. Where the water is corrosive to the water supply pump, treatment should be injected ahead of the pump.

Detergents detected in the source water must be deemed evidence of possible contamination, and the system must have equipment and/or treatment facility required for the removal or destruction of pathogens – unless, by tests acceptable to the cognizant health authority, the source can be shown to be free of pathogens both presently and potentially.

Nothing in this section shall require, or prohibit the use of equipment and/or treatment designed to remove the detergent. If used, it must be compatible with other treatments.

Water delivered by a private system should not contain sediment, turbidity, color, taste or odor in excess of an amount which would be esthetically offensive or hinder routine domestic operations. Where allowable limits are exceeded, suitable corrective equipment should be installed.