Most well water problems announce themselves through a symptom you can see, smell or taste, and each symptom points at a fairly short list of causes. The problem is that nobody regulates your well for you. The EPA notes that private wells are not federally regulated under the Safe Drinking Water Act, which means the testing, the diagnosis and the fix are all the owner's responsibility.
Nobody tests your well but you
The EPA reports that around 15 percent of the US population, over 43 million people in more than 23 million households, rely on private wells, and that those wells fall outside the Safe Drinking Water Act. The agency also cites a USGS study of 2,100 private wells which found about one in five carried at least one contaminant above a human-health benchmark. That is the frame for everything below: a well can look, taste and smell perfectly fine and still carry something worth knowing about, and the only way to find out is a laboratory test. Test at least annually for bacteria, nitrate and anything your local geology is known for.
Staining, color and metallic taste
Orange or reddish-brown staining in sinks, tubs and laundry is the signature of iron. Black or dark brown specks and staining point to manganese, often alongside iron. Both carry secondary aesthetic standards rather than health-based limits, with recommended maximums of 0.3 mg/L for iron and 0.05 mg/L for manganese according to Penn State Extension. Blue-green staining on copper fittings is different: that is acidic water dissolving the pipe itself, and it needs a neutralizer rather than a filter. Water that is clear from the tap and turns orange in the bucket carries dissolved iron; water that is already orange carries oxidized iron, and they need different equipment.
Smells: rotten eggs, musty, oily
The classic rotten egg smell is hydrogen sulfide, produced either in the aquifer or by sulfate-reducing bacteria living in the water heater. The test that separates them is simple: if only the hot water smells, the anode rod in the heater is the likely culprit; if hot and cold both smell, it is coming from the well. Musty or earthy odors usually mean surface water is reaching the well, which is a construction and sealing problem rather than a treatment one, and a strong prompt to test for coliform bacteria. Any petroleum or solvent smell should stop household use of the water immediately and go straight to a laboratory panel.
Cloudiness, grit and bacteria after events
Cloudy water that clears from the bottom up is air, which is harmless and usually a pump or pressure tank issue. Cloudiness that does not clear is suspended sediment, from the formation, a failing well screen, or surface intrusion. Grit that appears after heavy rain, or a coliform result that turns positive after flooding, both point at the wellhead itself: a cracked casing, a bad seal, or a cap that no longer keeps runoff out. Fix the well before you buy treatment, because a well that lets surface water in will keep defeating anything downstream of it. Our well water filtration system guide sets out the usual treatment order once the well itself is sound.
Questions people ask about well water problems
How often should I test my well?
At least annually for bacteria and nitrate, plus whatever your local geology or a change in taste, smell or appearance suggests. The EPA notes private wells are not federally regulated, so no one else does this testing for you.
Only my hot water smells of rotten eggs. Why?
That usually points to the water heater rather than the well, where the magnesium anode rod reacts with sulfate-reducing bacteria. Water that smells cold as well is coming from the aquifer.
Why does my water turn orange only after it sits?
That is dissolved iron oxidizing on contact with air. Because it is dissolved at the tap, a sediment filter will not catch it and an oxidizing iron filter is needed instead.
My water turned cloudy after heavy rain. Is that serious?
It can be. Sediment or turbidity after rain suggests surface water is reaching the well through a fault in the casing, cap or seal, so test for coliform bacteria and inspect the wellhead.