Grapevine Water Hardness and Your Pool: 2024 Report Numbers

Grapevine water hardness is 117 ppm for city water and 135 ppm for Trinity River Authority (TRA) water, according to the City of Grapevine’s 2024 annual water quality report. As of October 2026, that is the latest report on the city’s water quality page. Here is what the numbers say and how a pool owner can use them.

What does Grapevine’s water quality report say about hardness?

The report lists total hardness as CaCO3 at 117 ppm for Grapevine water and 135 ppm for TRA water. One grain per gallon equals 17.1 ppm. By that calculation, 117 ppm is about 6.8 grains per gallon and 135 ppm is about 7.9.

The report mixes two supplies. Grapevine treats water from Lake Grapevine and also buys water from TRA. TRA uses surface water from Lake Arlington, which is fed by Cedar Creek Reservoir and Richland-Chambers Reservoir.

The report also lists chloramines as the disinfectant. The annual average was 2.55 ppm, with a range of 0.5 to 4.0 ppm.

Is that the same as my pool’s calcium hardness?

No. Tap water numbers describe water in the city system. Your pool is a different thing. Water leaves a pool by evaporation, but the minerals stay behind. Each top-off then adds a little more. Over time, the pool can read very differently from the tap.

Calcium hardness is the pool test that matters. The city report can tell you what you are adding when you fill. It cannot tell you what is already in the pool.

How do I read ppm and grains per gallon?

The report states that ppm means parts per million, the same as milligrams per liter. Water softener ads and some pool charts use grains per gallon instead. One grain per gallon equals 17.1 ppm, so divide the ppm figure by 17.1 to convert. Those conversions are calculations and not city figures. Use ppm when you compare the report with a pool test, since most pool test kits report calcium hardness in ppm.

What can mineral-rich water do to tile, heaters and salt cells?

Minerals can build up as scale on tile, inside a pool heater and on a salt cell. Whether that happens depends on the whole balance, not on hardness alone. pH, total alkalinity, calcium hardness and water temperature all play a part. The Langelier saturation index combines them into one number.

Here is a simple way to think about it:

None of these signs prove a hardness problem. They are reasons to run a full water test. Our pool water chemistry chart lists the readings to check. If you run a salt pool, the saltwater vs chlorine guide explains the extra upkeep.

How should I use the report when I fill or top off my pool?

Use it as a guide for what goes in, then test the pool. The report is a yearly summary, so a single day can differ. Marina Pool Services weekly service covers water balance, including chlorine, pH, alkalinity, calcium hardness and conditioner, plus salt if your pool has a salt system. Read more on the weekly pool service page.

Steps to follow when you fill:

1. Test your pool before you add water.
2. Add water slowly and avoid overfilling.
3. Test again after the water settles.
4. Compare the new readings with your last test.
5. Ask a pro before you drain a large part of the pool.

A partial drain and refill can lower mineral levels, but it also costs water and can stress a pool. Local watering rules may apply, so check the city’s water conservation page first.

Where can I read the report myself?

The City of Grapevine posts the report on its water quality page. Look at the secondary constituents table near the end. It holds hardness, alkalinity, pH and dissolved solids. City reports change each year, so check the date on the version you open.

For more on pool care across the area, see our North Texas pool care guide and our Grapevine service page.

Next step

If your tile is crusty, your heater is slow or your salt system shows a scale warning, a water test is the place to start. See our pool maintenance services, call (817) 896-1120 or use the quote form at /contact.