If your St. Charles tap water smells faintly like a swimming pool, or tastes a little different than it used to, the cause may be a disinfectant called chloramine. It helps to understand what chloramine is, why a water system might use it, and how to check whether it is the source before you spend time or money on a fix.
What chloramine is
Chloramine is a disinfectant formed when chlorine and ammonia combine in water. Plain chlorine works quickly, but it fades as water travels through long stretches of distribution pipe. Chloramine lasts longer, which is why some water systems choose it to keep disinfectant present farther from the treatment plant.
Chloramine also behaves differently from chlorine at home. Plain chlorine dissipates when water sits open in a container for a while. Chloramine is much more persistent, so letting a glass sit on the counter will not clear it.
Why some St. Charles homes notice it
Local water reports for St. Charles describe chlorine disinfection, and they describe the water as hard, with pH readings that are unusually high. Those reports do not tell you which disinfectant reaches your particular tap. Check the most recent annual water quality report for your address, or contact your water provider and ask directly whether chloramine is in use and whether that changes at certain times of year.
Homeowners usually notice chloramine in a few situations:
- A smell or taste that resembles chlorine, which can be more noticeable in warm weather.
- Water that smells strongest when it first comes out of the tap after sitting in the pipes overnight.
- A difference between the kitchen tap and a bathroom tap in the same house, especially in older homes where pipe runs are long.
- Stress or losses among fish or other aquatic animals after a water change, since chloramine affects aquatic life.
A change you notice in summer may not be a change in your home. It may reflect a seasonal shift in the water system, so keep a short log of when you notice the smell or taste.
How to check at home
Start with a simple test. Many test strips and drop kits report total chlorine, and a separate free chlorine reading helps you judge how much of the disinfectant is bound up as chloramine. The gap between the two readings is the usual clue. Collect the sample from a cold tap as the kit directs, and write down the date, time, and the tap you used. A water lab can give a more complete report if you want a definite answer.
What removes it
Letting water stand does not remove chloramine the way it can with plain chlorine. Boiling does not remove it either. Activated carbon can reduce chloramine, but standard carbon is not always enough. Filters made for chloramine use catalytic carbon designed for that job. Read the filter's own performance information, confirm it names chloramine, and follow the replacement schedule, since spent media stops working.
Next steps for a St. Charles homeowner
- Read your most recent water quality report and look for the disinfectant it names.
- Ask your water provider in writing whether chloramine is used in your area and whether that changes seasonally.
- Test your tap with a kit for total and free chlorine, and note the time and temperature of the sample.
- If you keep fish or an aquarium, treat new water with a dechlorinator labeled for chloramine before adding it to the tank.
- If you want to treat drinking or cooking water, choose a carbon filter that states chloramine reduction, and keep up with its replacement schedule.
Chloramine is one of several reasons tap water can change from one room to another in a St. Charles home. Your report, a simple test, and a log of when you notice the change will show which explanation fits your house before you choose any equipment.