WATER QUALITY LIMITS RECOMMENDED BY THE ENVIRONMENTAL PROTECTION AGENCY FOR LIVESTOCK
Aluminum The level of protection has been recommended to be no more than 5 mg/L. This level will occur only in extreme cases.
Arsenic The recommended safe level has been set at 0.2 mg/L.
Boron Needs further testing, but EPA recommends 5.0 mg/L as maximum concentration.
Cadmium Very toxic and an upper limit of 0.05 mg/L is given.
Chromium A limit of 1.0 mg/L is allowed.
Cobalt Few waters have more than the 1.0 mg/L safe level.
Copper Very few natural waters will exceed the 0.5 mg/L limit.
Fluoride A limit of 2.0 mg/L is recommended.
Lead Unlikely to be found in natural waters, but a safe level of less than 0.1 mg/L is recommended.
Mercury Adhere to a limit of 0.01 mg/L i water to prevent toxic accumulation in animal products.
Nitrate and nitrite nitrogen Should be limited to 100 mg/L.
Nitrite nitrogen Nitrite nitrogen content alone should be less than 10 mg/L.
Selenium Poisoning by water has not been substantiated, but a limit of 0.05 mg/L is recommended.
Zinc Relatively nontoxic but has a limit of 25 mg/L.

Reference:

Water Quality Criteria 1972, A Report of the Cmmittee on Water Quality Criteria, Environmental Studies Board, Washington D.C. 1972.