Zinc is a essential and beneficial element in human growth.  Concentrations of 5 ppm can cause a bitter taste in alkaline waters.

Acceptable results:  There are no health standards but less than 5 ppm is ideal.

Sources:  Zinc most commonly enters water from deterioration of galvanized iron and dezincification of brass.  Zinc in water also may result from industrial waste pollution.

Recommended testing:  If in a risk area or a bitter taste to the water is detected.