The tap report, read one line at a time

WSSC Water’s quality report for 2025 lists yearly averages by plant, and on the 10 lines here the Potomac reads equal or higher except pH, which is 7.3 against Patuxent’s 7.5.

By the Your Water Numbers desk, not WSSC Water · Updated November 2, 2026 · How we check

Reading this: Each cell is a yearly average, with a range in brackets where we have one. A plant average is not a reading from your faucet.

Which lines have a limit beside them?

Four here have a stated limit or standard. Nitrate sits at 0.8 and 1.0 against a limit of 10. Fluoride is 0.7 at both plants against a secondary level of 2. Chloride runs 43 and 51 against a secondary limit of 250.

pH of 7.5 and 7.3 falls inside the secondary range of 6.5–8.5. Secondary limits mostly concern taste, look and feel. Residual chlorine works the other way round, with a minimum of 0.2 that both plants clear.

Why does the Potomac read higher on most lines?

The two plants draw from different rivers, and the Potomac runs higher on minerals in these figures. Conductance shows it in one number: 437 µS/cm against 241. Conductance rises with dissolved minerals.

What does the chlorine line mean for taste?

It means disinfectant is meant to be there. Residual chlorine averaged 1.3 at Patuxent and 2.0 at Potomac, with a required minimum of 0.2. Taste is a personal call, and it isn’t a safety signal in these figures.

If it bothers you, a carbon filter is the usual household answer. If the water tastes fine, skip it. Neither link below is a lead recommendation, and no line in this table makes either one necessary.

Can you read hardness from the calcium line?

Partly. Calcium is one piece of hardness and the two move in the same direction, 19 and 46 against 70 and 154. The full story is on our hardness page, including the grains conversion, and on what hard water does to a heater.

What’s missing from the lines we list?

Three things worth knowing. TDS isn’t listed, so conductance is the nearest stand-in. Lead sits in a separate report, the 2025 Water Quality Report, covered on our lead page. PFAS has its own results page.

The report also can’t speak to your pipes. What happens between the main and your glass is a separate question, and who owns which pipe covers the first step.

Why won’t your own test match these?

Because these are yearly averages at the plant level, and yours is one sample at one tap. Hardness alone ranges from 79 to 213 on the Potomac. A home reading inside the range agrees with the report, even if it’s far from 154.

Questions on this page

Where each number comes from