What Clarksville's 2025 water report shows

Each summer the City of Clarksville prints its Annual Drinking Water Quality Report inside the CGW customer magazine. The 2026 edition covers January 1 to December 31, 2025. It states that the water "meets or exceeds all federal and state drinking water standards", and every row of the regulated table carries a "N" in the violation column.

Where does Clarksville's tap water come from?

It is surface water drawn from the Cumberland River and treated at the Clarksville Water Treatment Plant. The plant filters with hollow-fiber membranes of 0.1 micron nominal pore size, small enough to hold back Cryptosporidium and Giardia, which the report sizes at 3 to 15 microns. The state's source water assessment rates the river as reasonably susceptible to contamination, the highest of its three levels. That rating describes the raw river, which is why filtration and disinfection matter so much here.

How close did each reading come to its limit?

None reached two-thirds of its limit. We divided each 2025 reading by its federal limit to put different units on one scale; the two disinfection byproducts sit highest, then chlorine itself.

Copper uses the 90th-percentile result from 50 homes sampled in June 2024, the most recent round in the report. Lead is left off the chart because its 90th percentile was "ND", not detected at the 2 ppb reporting level; our lead service lines page covers those samples.

What are TTHM and HAA5, and why are they the highest?

They are byproducts that form when chlorine meets natural organic matter from the river. The report gives them as locational running annual averages: total trihalomethanes 49 ppb (range 29 to 63) and five haloacetic acids 35 ppb (range 17 to 43), against federal maximums of 80 and 60. Even the highest single results, 63 and 43, stayed below those annual limits.

Does Clarksville use chlorine or chloramine?

The report lists chlorine. The 2025 level averaged 2.0 ppm with a range of 0.3 to 3.2, under the maximum residual limit of 4.0. Taste and odor fall under EPA's secondary standards, which are not health limits. That residual is what you may taste or smell at the tap, and it keeps germs from growing in the pipes between the plant and your house.

Is there PFAS or fluoride in the water?

All 29 PFAS compounds in EPA's fifth unregulated monitoring round, plus lithium, came back below the minimum reporting level in 2024 and 2025 samples, PFOA and PFOS included. The report does not print those reporting levels. Fluoride averaged 0.46 ppm (range 0.38 to 0.56), about a ninth of the 4.0 limit.

What else in the report matters inside the house?

A page near the back warns about thermal expansion. Check valves in meters, backflow devices and pressure-reducing valves can close off a home's plumbing, so heated water has nowhere to expand and pressure climbs; the report says this "may damage water heaters" and that expansion tanks are often installed. If your heater's relief valve drips after each heating cycle, ask a licensed plumber whether expansion is the cause, and never cap or plug that valve; our water heater temperature page covers the heater side. Hardness sits on a separate CGW characteristics table and gets its own hardness page here.