Smelly, stained or cloudy well water

Causes and what to test

Minnesota Department of Health lists sulfur bacteria living in the groundwater, the well or the plumbing as one source of the smell, along with natural decay and reactions inside water heaters.

To find the source, the Minnesota Department of Health suggests smelling the hot and cold taps after the house has sat unused for a few hours; a smell only in hot water points to the water heater.

The Minnesota Department of Health says the rotten egg smell usually is not a safety problem, but rarely it comes from sewage, so it advises a coliform bacteria and nitrate test to be safe.

Texas A&M AgriLife Extension says iron leaves reddish brown stains and manganese leaves brownish black stains on laundry, sinks and fixtures, and ordinary detergent does not remove them.

Texas A&M AgriLife Extension notes EPA secondary (nuisance, not health) limits of 0.3 mg/L for iron and 0.05 mg/L for manganese; below those levels water should not taste, smell or look bad.

Texas A&M AgriLife Extension recommends a lab test that also measures pH, oxygen, hardness and sulfur, because those decide which treatment will work.

The Minnesota Department of Health says yellow or red water usually means iron, but only a lab test gives the exact amount needed to pick a treatment; it also suggests testing hardness, pH, alkalinity and iron bacteria.

Sources: Rotten egg smell is hydrogen sulfide; Iron stains red, manganese stains black; Colored water is a clue