If your Wentzville tap water has a chlorine smell or taste, or if you use a filter that is supposed to reduce chlorine, a test strip can show you what is in the water at the moment you test. Chlorine checks are easy to repeat, and they let you compare the water at different taps in your home. This guide explains what the readings mean and how to take one you can rely on.
What the Two Readings Mean
Most chlorine strips report two numbers. Free chlorine is the disinfectant that is still available to act on germs in the water. Total chlorine includes the free chlorine plus any chlorine that has already combined with other substances in the water. The gap between the two readings is called combined chlorine. A large gap can point to the chemistry of the water, not just the amount of disinfectant added.
Your Wentzville water report also lists disinfection byproducts such as TTHMs and HAA5. These form when disinfectants react with natural organic matter in the water. A strip cannot measure those compounds, so do not treat a chlorine reading as a stand-in for them. A strip can only show you how much disinfectant is present at a given tap on a given day.
Before You Test
- Buy strips that list both free and total chlorine on the label, and check the expiration date on the bottle.
- Keep the strips sealed and dry. Humidity in a basement or laundry room can change the color before you ever open the bottle.
- Read the color chart in good light, holding the strip beside the chart rather than in shadow.
Taking the Sample
- Run the cold tap until the flow runs steady and the water feels cool.
- Fill a clean glass or plastic container, or test directly from the stream if the strip instructions allow it.
- Dip the strip for the time listed on the label, then shake off the extra water.
- Compare the color within the time window on the label. Colors keep changing, so a late reading is not reliable.
- Write down the free reading, the total reading, the tap you tested, and the time of day.
Compare More Than One Tap
A single reading tells you very little. Test the kitchen cold tap, then a bathroom cold tap farther from the water heater, and an outdoor spigot if you have one. Use the same steps at each location. If the readings drop as you move farther from the main line, the difference may point to your home plumbing or to water that has been sitting in a pipe or storage point. If the readings stay about the same, the water is consistent through the house.
Testing Before and After a Filter
If you have a carbon filter or a whole-house filter, test before and after it. Use the same tap and the same method both times. A filter that reduces chlorine should show a lower reading after it, and the gap between the two readings tells you whether the filter is still doing that job. Do not assume a filter is working because the water tastes better. Taste can change for other reasons, and a strip reading is the more direct check.
Private Wells Work Differently
Public water systems usually add a disinfectant, so a residual is expected at your tap. Private wells usually have no disinfectant unless the owner has installed a treatment step. If your Wentzville home draws from a well, a chlorine reading tells you whether any disinfection is in place, but it does not tell you whether the water is free of bacteria. Coliform and E. coli need a laboratory sample. This matters for river-bottom alluvial wells and deep bedrock wells in the area, where water quality can vary widely from one property to the next.
When a Strip Is Not Enough
Strip readings are a screening tool. If a reading is lower than you expected, or if it changes suddenly, ask your water provider which disinfectant the system uses and whether there have been recent maintenance notices. For a private well, ask a certified laboratory about a full test panel. Keep a running log of your readings so you can see patterns across weeks and seasons, and bring that log with you when you talk to a lab or a provider.