If your dishwasher leaves a rust-colored film on glassware or gives the tub an orange tint, the water supply is the first suspect, but it is not the only one. Many homes in St. Louis have iron in the water at levels that may not be noticeable at the kitchen tap, and a dishwasher can make the problem easier to see. Here is a plain way to sort out where the color is coming from.
Start With the Kitchen Sink
Run the cold tap at the kitchen sink until the water runs cold, then fill a clear glass and hold it up to a window or a light. If that water is also orange, yellow, or cloudy, iron is likely in the supply. If the sink water is clear, the problem is more likely inside the dishwasher, in the detergent, or on the dishes themselves.
Check the hot tap too. If only the hot water looks rusty, the water heater may be involved, since heated water can make iron deposits more noticeable. Compare the hot and cold results before you change anything else.
Look at the Dishwasher Itself
Dishwashers can carry rust-colored residue from several places. The inlet screen near the water valve can catch sediment and rust flakes. The spray arms can clog with debris. A drain filter at the bottom of the tub can hold food particles and mineral deposits that discolor the water as it cycles.
- Pull out the lower rack and look at the bottom of the tub for orange flakes or a film.
- Remove the filter and rinse it under running water with a soft brush.
- Check the spray arm holes and clear any blockage.
- Look for an inlet screen where the supply line connects, if your model has one.
Your owner's manual shows where each part sits, since layouts differ by model. If you cannot find a part, a repair technician can point it out during a visit.
Check the Supply Line and Shutoff Valve
The supply line running from the shutoff valve under the sink can carry rust flakes, especially if it is an older metal line. Look for rust at the fittings and along the hose. If you decide to inspect further, shut off the valve, disconnect the line at the dishwasher end, and look at the screen in the valve or the end of the line. Reconnect carefully, turn the water back on, and check for leaks before you walk away.
If the supply line is old and shows rust in several places, replacing it is a reasonable step to consider. This is a repair decision, so compare what you find with what a licensed plumber recommends for your home.
Consider Detergent and Rinse Aid
Some detergents and rinse aids leave a film on dishes, and that film can look like rust when it mixes with iron already in the water. Try one full cycle with a different detergent, or without rinse aid, and see whether the film changes. Use only the amount printed on the product label, and avoid adding extra product to fix a film problem.
Test the Water Before Blaming the Machine
A simple home test kit can show whether iron is present in your water, and a certified lab can give a more detailed answer. Many St. Louis homeowners on city water can also request the annual water quality report from their water provider. That report describes the water leaving the treatment plant, not the water after it travels through your home's pipes, so iron can still enter or change along the way.
If the sink water shows color, the supply is the likely source, and a water treatment specialist can test the water and explain the options. If the sink water is clear and the dishwasher still shows the problem, the cause is more likely in the appliance or the detergent.
When to Call for Help
Call a water treatment specialist when the sink water is orange, cloudy, or stains fixtures, since that points to the supply. Call a repair technician when the sink water is clear but the dishwasher still leaves residue after you have cleaned the filter, spray arms, and tub. Keep short notes on when the color appears, which taps show it, and what changes you made. That record helps whoever you contact understand the pattern faster.
Quick Checklist
- Compare cold sink water with dishwasher water in a clear glass.
- Clean the dishwasher filter, spray arms, and tub bottom.
- Inspect the supply line screen and fittings for rust.
- Switch detergent or rinse aid for one full cycle.
- Test or send a sample to a lab if the sink water also shows color.