Many homeowners notice a swimming-pool taste or smell and assume something is wrong with their pipes. Usually the water is carrying a disinfectant that the public supply added on purpose to kill germs as the water travels through the mains. That is normal, but it is still unpleasant, and it is a real reason some households decide to add a treatment unit. Before you spend money on one, confirm what is actually in the water.
What the smell usually means
Free chlorine can smell like bleach or a pool, and the smell is often strongest right after the water is drawn. It tends to fade if the water sits in an open glass for a while. Chloramine, a combination of chlorine and ammonia that some utilities use, has a weaker smell but a more persistent taste, and it does not leave a glass the way free chlorine does. Those two disinfectants respond differently to filtering, so you need to know which one you have.
Checks you can do yourself
Run the cold tap for a minute, fill a clear glass, and set it on the counter for about fifteen minutes. If the smell fades noticeably, free chlorine is the likely cause. If the smell stays about the same, suspect chloramine or a source inside the house.
Compare the cold tap with the hot tap. A taste that appears only on the hot side points toward the water heater or the hot-side plumbing, such as sediment or a dissolved gas in the tank, rather than the supply.
Check one fixture against the rest. If only one faucet smells, the cause may be local, such as a dirty aerator, an old filter cartridge, or a drain trap. A smell at every tap points to the supply itself.
Ask the utility for its most recent annual water quality report. The report names the disinfectant the utility uses. Keep a copy, because any provider you talk to will ask for it.
What to ask before you buy a unit
Ask the provider which disinfectant the unit is rated to remove, and whether the rating applies to your utility's disinfectant specifically. Standard activated carbon handles free chlorine well, but chloramine usually needs a specific carbon or catalytic type, so a general claim is not enough. Ask whether the provider tested your water or is working from the utility report alone.
Ask whether the unit is meant for a single tap or the whole house. Ask to see the certification mark or the test results behind the performance claim, not only a brochure. Our methodology page explains how we review providers, which is a useful comparison point when you read a company's own claims.
When to call the utility first
If the taste changes suddenly, shows up with a change in color, or follows notice of work on the mains, call the utility before you call a treatment company. The utility can tell you whether its disinfectant or treatment process changed. If anyone in the household has a health question about the water, take it to their doctor and to the utility, since those are the people who can answer it properly.
If you do decide to compare providers, the directory of water treatment providers in Missouri is a place to start, but keep the utility report in hand while you compare.