If you have ever opened a St. Peters water report and felt lost in the table, you are not alone. Two rows that show up often in local reports are TTHMs and HAA5. The names sound technical, but the idea behind them is simple, and you can read them with a few steps.
What TTHMs and HAA5 Are
Both belong to a group called disinfection byproducts. Water providers add disinfectant to keep bacteria in check as water travels through the pipes. That disinfectant reacts with natural organic material already present in the source water, which in St. Peters comes from a mix of river water and groundwater. The reactions form compounds nobody adds on purpose. TTHM stands for total trihalomethanes, and HAA5 refers to a group of haloacetic acids. Reports list both because they are sampled on a schedule across the distribution system.
Where to Find the Results
Your water provider publishes an annual water quality report, usually posted online and sometimes mailed with the bill. Look for the section on disinfection byproducts, then work through these items:
- Find the row for each group and note the reported result.
- Check the limit or comparison value listed beside it.
- Read the units column so you know what the result is measured in.
- Look for the sampling year and whether results are a running average or a single sample.
- Note any violation or public notice language in the same report.
If a result is close to the comparison value, the report will usually explain how it was calculated. Reading that explanation matters more than the single number.
Why a Softener Does Not Change These Readings
A water softener is designed to exchange hardness minerals, mainly calcium and magnesium, for sodium or potassium. It is not built to remove disinfection byproducts. A softened tap in St. Peters can show the same TTHM and HAA5 results as an unsoftened one, so a softener alone will not change these rows in the report. If you want to address them at home, the usual approach is a separate treatment step, not a change to the softener.
Testing Your Own Tap
System averages describe the water across the service area. They may not match what comes out of your faucet, especially if your home sits at the end of a long line or your plumbing adds its own variables. To get a reading for your own home, use a certified laboratory.
- Ask the lab for its sampling kit and written instructions, and follow them exactly.
- Note whether the sample came from the cold or hot side, since the instructions usually specify one.
- Let the lab know if you want a sample collected after the water has sat in the pipes, and if you want one after flushing.
- Keep the lab report with your home records so you can compare future results.
- Ask whether the lab reports results in the same units your water provider uses.
Questions to Ask Your Water Provider
- Which sampling sites serve my street, and how close are they to my home?
- How often are TTHMs and HAA5 tested, and when was the most recent round?
- Has the system had any recent changes to its disinfection process?
- Where can I find the full results behind the summary table?
Deciding What to Do Next
Start with the report, then decide whether a home test would answer a real question for you. If you are considering treatment, check whether any product you look at lists certification for the specific compounds you care about, and ask a qualified professional to explain how it would fit your plumbing. Do not rely on a general claim about any filter.
This guide is general information for homeowners in St. Peters, not medical advice. If you have questions about your health or your household, talk with your doctor.