If you live in St. Louis and notice orange, brown, or rusty-looking stains in your sink, tub, or toilet bowl, the water supply is one possible source. Iron is a common mineral in groundwater, and when dissolved iron meets air, it can oxidize and leave a reddish or brown mark on porcelain, enamel, and grout. Other sources, like corroded fixtures or rusting fittings, can cause similar stains, so it helps to narrow things down before you spend money on any equipment.
What the stain pattern can tell you
Start by looking closely at where the stain appears and how it behaves. Water-related iron stains usually show up around the drain, under the faucet, or along the bottom of a basin where water sits. They often return soon after cleaning, and they may be worse on the hot side.
- Stains only on one fixture point to that fixture, such as a worn faucet cartridge or a rusting supply line.
- Stains on several fixtures, plus rust-colored marks on laundry, suggest the water supply itself.
- Stains that appear mainly on the hot side can point to the water heater or hot water piping.
- Stains around a toilet tank or bowl rim often trace back to the tank parts or the fill valve.
Simple checks you can do at home
- Look at the faucet aerator and remove it. A dark or flaky buildup inside it may be rust from the supply line.
- Run the cold tap alone for a minute, then the hot tap alone. Note which side produces the color.
- Draw a glass of water and let it sit for a short while in good light. A reddish tint or cloudiness that settles out suggests particles.
- Check the laundry. Rust-colored spots on white clothes that were washed in your home water are a useful clue.
- Write down when the stains appear, such as after a long dry spell, after a water main repair in your area, or after using the water heater for a long time.
Testing the water for iron
Visual checks can narrow the problem, but they cannot confirm iron. A water test from a certified laboratory will report the level of dissolved iron and other minerals in your water. Ask the lab for a report that lists iron separately from other metals, since a general hardness test will not answer the question. Keep the report with your home records so you can compare results over time or share them with a service professional.
Home test strips and drop kits can give a rough reading, but they are less reliable for deciding what equipment to install. Use them as a screening step, then confirm with a lab if the results matter for your decision.
Where a reverse osmosis unit fits in
A reverse osmosis unit is designed to reduce many dissolved minerals, and that includes iron, but it treats only the water that reaches it. If your stains come from fixtures or pipes downstream of the unit, a filter at the sink will not remove them. A plumber can check where the rust is entering the system before you decide whether a point-of-use unit, a whole-house treatment system, or fixture repairs make the most sense for your St. Louis home.
Do not expect any single product to clear every stain on its own. Some stains already on porcelain will need a cleaner made for that surface, and old rust deposits inside pipes may take time to flush out.
When to call a plumber
- The stains spread to several fixtures and the lab results point to iron or another metal.
- The water comes out with a strong rusty smell or with visible particles that do not settle.
- You see green or blue staining on copper fittings, or pinhole leaks, which can point to corrosion in the pipes.
- The hot side is much worse than the cold side and the water heater is older.
Keep your lab reports, notes about where and when stains appear, and photos of the affected fixtures. These records help whoever you call figure out the source faster and avoid repeated visits.