If your St. Louis tap water suddenly smells like chlorine, tastes flat or metallic, or has a faint earthy or rotten odor, the first job is to figure out where the change starts. Most homes in the city and nearby county get water from a treatment plant through a long network of mains and service lines. Several points along that path can change how the water smells or tastes. Many changes are temporary and easy to trace. A few deserve a phone call to your water provider.
Find out whether it is the whole house or one fixture
Start with a simple comparison. Run the cold kitchen tap, then the cold bathroom tap, then an outdoor spigot if you have one. If every cold tap shows the same change, the cause is likely in the supply coming into the home or in treatment at the plant. If only one fixture is affected, or only the hot side, the cause is more likely inside your plumbing or an appliance.
Common causes in St. Louis homes
- Seasonal shifts in the source water or treatment adjustments, which can briefly change the chlorine smell or taste.
- Water main work or pressure changes on your street, which can stir up loose sediment in the lines.
- Water that sat still in pipes or fixtures while the home was unused for a day or more.
- Sediment or a chemical reaction inside a hot water heater, which often shows up as a rotten egg or metallic smell at the hot tap only.
- Drain odors from a dry trap or a slow drain, which can drift into a glass left near the sink.
- An old or saturated refrigerator filter or under-sink filter that is past its change date.
- Iron or manganese in the supply, which can cause a metallic taste and yellow, brown, or black staining.
Simple checks you can run this week
- Fill a clean, clear glass from the cold tap. Smell it right away, then again after a few minutes with the glass uncovered.
- Run the cold tap for several minutes to clear the line, then fill a fresh glass and compare.
- Test water from a tap that has not been used for a day. If it smells different from water that has been running, the issue is likely standing water in your plumbing.
- Check the change dates on your refrigerator filter and any under-sink filter, and replace any that are overdue.
- Look at the water in a clear glass for color, cloudiness, or particles. Note whether anything settles to the bottom.
- Write down the date, which tap you used, and what you noticed. A clear record makes the next conversation with your water provider much easier.
Check the water heater before blaming the city
If the change only happens at the hot tap, the water heater is the most likely source. Sediment builds up at the bottom of the tank over time, and some heaters react with the anode rod in ways that produce an odor. Running the hot tap briefly and checking whether the smell fades can help you judge. If it does not fade, or if the water looks rusty, a plumber can flush the tank and inspect the anode rod. Ask for a written description of what they found.
Look up your water provider's report and ask questions
Your water provider publishes an annual water quality report, usually on its website. Read the section on treatment and any notes about recent changes. Then call the provider and ask two things: whether any main work, flushing, or treatment changes are scheduled near your address, and whether they have received other complaints about taste or odor in your area. Those answers help you decide whether the problem is temporary.
When to stop guessing and get a lab test
If the change lasts after you have flushed the lines, checked your filters, and ruled out the water heater, a certified lab test is the practical next step. Choose a test that matches what you noticed, such as a test for a specific metal or for bacteria, rather than a general screen. Keep the sample container clean and follow the lab's collection instructions exactly.
Two situations need action right away. If you smell gas, leave the home, avoid switches and flames, and call your gas provider or emergency services from outside. If the water is cloudy, dark, or discolored in a way that is new and does not clear after running the tap, stop using it for drinking and cooking until you have talked to your water provider. If anyone in the home has a health concern tied to the water, speak with a doctor.