Brown or tea-colored water from an O'Fallon tap is alarming to see, but it is usually easier to narrow down than it first looks. The color does not tell you what is in the water. It only tells you that something is dissolved or suspended in it. The useful next step is working out which kind of material it is.
Start with when the color shows up
- Color in every cold tap, all day, points to the source or the well itself.
- Color that appears only after water has stood overnight, or only in the first draw in the morning, points to standing water in pipes or a tank.
- Color that comes and goes after heavy rain or a dry spell points to surface influence or changing groundwater.
- Color only in hot water points to the water heater, not the supply.
Know the usual suspects
Tannins are natural organic compounds released as plant material breaks down. They give water a tea or weak-coffee tint and can show up in shallow wells and surface-influenced supplies. Tannins usually do not leave a sharp rust-colored stain, and a homeowner cannot judge them by eye alone.
Iron, and sometimes manganese, can make water look yellow, orange, or brown. Dissolved iron is often clear when drawn and turns brown as it sits and oxidizes. Particulate iron is already solid and shows up as visible specks or a layer in a glass. Iron bacteria can add slime and a deposit that looks similar, so note whether there is any slimy film on fixtures.
Sediment, such as sand, silt, or scale that breaks loose after pipe work or a pressure change, usually clears once the tap has run until the water is steady. It often settles in a glass as a distinct layer.
Run a simple glass test
- Run the cold tap until the water is steady, then fill a clear glass.
- Look at it in daylight against a white background and note the color.
- Let the glass stand for a while and look again. Brown material settling at the bottom suggests sediment or particulate iron. Clear water that leaves a rust-colored film on the glass suggests dissolved iron that has oxidized.
- Smell the water. A rotten-egg odor points to hydrogen sulfide, which is a separate issue with its own tests.
- Repeat the test at the hot tap. Color only there points to the heater.
Match the color to a test
A glass test narrows the question but does not answer it. For a private well, the MO State Public Health Lab offers coliform and E. coli testing, and iron-bacteria testing is also available. Ask the lab what else it can run for iron and manganese, since those usually need a separate analysis. Tannins are not covered by a single standard test. If the color persists and iron results come back low, a broader water analysis from an accredited lab may be needed.
O'Fallon tap water is described in public reports as hard, which is a separate issue from color. Brown tint from a public supply is less common. If you suspect the municipal water itself, check the most recent annual water report and contact your water provider with the date, time, and what you observed.
What to do before you treat
- Do not add a filter for color until you know whether the cause is iron, tannins, or sediment.
- If only hot water is affected, check the water heater drain for sediment before blaming the supply.
- Keep notes on the date, weather, time of day, which fixtures are affected, and whether the color cleared.
- Check faucet aerators and shower screens for trapped debris.
- If you have a private well, look for your well log and check the cap and casing for anything loose or damaged.
When to get help
If the color is new, comes with a strong odor, or appears in water you use for drinking or for infant formula, avoid using it for those purposes until results are in. Bring your glass-test notes and any lab results to whoever is helping you decide the next step. A clear diagnosis first keeps you from buying equipment for the wrong problem.