Document Znyxo7pb4OQr79D60QebnqmK7

INDUSTRIAL SANITATION AND PERSONNEL FACILITIES tarainabon of the water supply is direct or indirect cross-connection with a source of contaminated water. Other common causes are improper maintenance of drinking and cooking facilities and improper installation of plumbing facilities, permitting back-siphonage of used water The integrity of the drinking water sys tem must be mamtamed throughout the plant If there are piping systems contain ing water used for other purposes, such as sprinklers and fire hydrants or manufactur ing processes, each should be clearly identi fied, particularly at outlets There should be no direct connection between drinking water and other water systems Long dead end runs of pipe which cannot be Bushed or drained and which might serve as a reser voir for contaminated water should also be eliminated Plumbing Fixtures and faucets should be installed to prevent back-siphonage of contaminated water if the pressure drops m the supply Une Faucets and similar outlets should be at least 1 in above the floodrun of the re ceptacle beneath To prevent backflow into the drinking water supply, surge tanks and air gaps may also be required in the drain age lines from process equipment Open joints in underground supply hues into which ground water or water from leaky sewers can seep are another common source of contammabon This condibon may arise where pipes are subject to vibra tion or corrosion and the joints between pipes open mechanically or the pipe secbons crack Codes usually prohibit sewer and drinking water lines to be installed in the same bench, unless the sewer bne is placed at a much greater depth and a cer tain horizontal offset provided Frequently, contammabon results when a system is opened for repair or the addibon of new pipe and is not disinfected before being put back into service If the supply for sprinklers and fire hy drants is the same as that for drinking TABLE 37-A RECOMMENDED LIMITING CONCENTRATIONS OF CONTAMINANTS IN DRINKING WATER Undesirable Substance Concentrations above which water should not be used if other sources are available (mff/L) Alkyl benzene sulfonate Arsenic Chloride Copper Carbon chloroform extract Cyanide Fluonde Iron Manganese Nitrate Phenols Sulfate Total dissolved solids Zinc 05 001 250 1 02 0 01 See Table 37-B 03 0 05 45 0001 250 500 5 Dangerous Substance Arsenic Barium Cadmium Chromium (hexavalent) Cyanide Fluonde Lead Selenium Sih er Concentrations above which eater supply should be re jected (mg/L) 005 10 0 01 005 02 See Table 37-B 005 001 0 05 From Dnnktnff Water Standards U S Public Health Service 1962