New Braunfels Hard Water and Your Pool Surface
New Braunfels Quality Pool Resurfacing explains what New Braunfels hard water does to a pool's finish and tile. Hardness here comes with the groundwater, and the city's water utility names the minerals: extra calcium and magnesium. In a pool, that shows up as scale: a white crust at the waterline and a dull film on the finish.
The fix is balanced water, not softened water, because a soft fill damages cement finishes. Scale already built up on the finish can come off with a pool acid wash. Calls about hard water and scale are answered 24/7, and estimates are free.
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How hard is New Braunfels water?
New Braunfels Utilities draws most of the city's water from the Guadalupe River and adds groundwater from the Edwards and Trinity aquifers. Its hardness shifts with location, source and season, the utility says. State records show these total-hardness results for the utility's treated water, measured as calcium carbonate:
- January 24, 2024: 184 mg/L
- May 8, 2024: 296 mg/L
- January 28, 2025: 180 mg/L
- April 2, 2025: 274, 285 and 292 mg/L at three entry points
- July 16, 2025: 281 and 406 mg/L at two entry points
- January 14, 2026: 203 mg/L
The U.S. Geological Survey grades water from 0 to 60 mg/L as soft, 61 to 120 as moderately hard, 121 to 180 as hard and anything above 180 as very hard. On that scale, the January 28, 2025 sample was hard and every other result very hard. A milligram per liter (mg/L) equals one part per million (ppm), the unit pool water ranges use.
Why New Braunfels hardness readings vary
The three lowest results all came from one entry point at 2356 Gruene Road, the address of the utility's surface water plant. State records don't say which source feeds which part of town.
The minerals come with the groundwater, the utility says. A state water agency describes Edwards Aquifer water as hard but fresh, and Trinity water as very hard where that aquifer reaches the surface. Boil Edwards water dry and the white residue left in the pot is dissolved limestone, says the agency that manages that aquifer.
Not every home in the area is on the utility's water, and these figures are the utility's only. Neither its yearly reports nor the state samples list iron or manganese, two metals behind some pool stains. The National Plasterers Council advises testing fill water for metals as well as for hardness.
Alkalinity runs high too
The same records show total alkalinity from 133 mg/L on January 24, 2024 to 262 mg/L on May 8, 2024. On August 17, 2026, four entry points read 233 to 236 mg/L. The council's range for pool water is 80 to 120 ppm of carbonate alkalinity. Its start-up card begins by testing the fill water and bringing high alkalinity down to 80 to 100 ppm with diluted muriatic acid.
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(830) 302-4112
What hard water does to pool finishes and tile
Hardness is the amount of dissolved calcium and magnesium in water, the U.S. Geological Survey says. When pool water holds more than it can keep dissolved, the extra comes out as scale: minerals that cling to tile and finish and leave stains and roughness behind.
On the finish
Scale shows as a white or light film that mutes the finish color, or hides it entirely, the council says. It ranks among the three main causes of color loss in a pool. High calcium, high alkalinity and a high pH each push water toward scale.
Warm water leans the same way. In the council's saturation table, the temperature factor rises from 0.6 at 76°F to 0.9 at 105°F, and a higher index means more scaling. A water-test maker advises checking the balance in summer and in winter for that reason.
On the tile
Evaporation leaves calcium behind, so the waterline tile takes the worst of it. That white band counts as scale even out of the water, a pool chemical maker says. Too high a pH can also form deposits beneath tiles, a tile-setting maker says, where they push on the tile and can weaken its bond.
On fiberglass, vinyl and spas
Other surfaces scale too. One fiberglass pool maker says scale forms on its gelcoat (the colored resin surface) whenever pH tops 7.4 with calcium hardness above 120 ppm. It adds that a fiberglass pool rarely, if ever, needs calcium added. A high pH also leaves scale on vinyl liners, a liner maker notes. And heat speeds it up: hard water forms calcium carbonate deposits when it's heated.
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(830) 302-4112Balancing hard water in a pool
The goal isn't soft water. It's balanced water, which neither leaves scale nor eats into the finish. The council measures that balance with the saturation index, a calculation from pH, alkalinity, calcium hardness, temperature and dissolved solids. Below zero, water dissolves the finish; above zero, it leaves scale. The council's ideal is 0.0 to +0.3.
Tap and pool readings aren't the same thing. Total hardness counts calcium and magnesium together, while the council's 200 to 400 ppm is calcium hardness alone, so test the pool water itself.
Don't soften the fill water
Softening the fill to avoid scale backfires on a cement finish. The council recommends fill water above 200 ppm of calcium hardness, and says soft water damages these finishes, from heavy discoloration to a weaker binder and a shorter life. Its fix for a softened supply is to bypass the softener during the fill.
Testing and treating hard pool water
The council suggests testing pH, alkalinity and chlorine once or twice a week, and calcium hardness, stabilizer and dissolved solids once a month. Sequestering or chelating products can hold minerals in solution, it adds, but once started they have to stay in use for as long as those minerals remain. Texas holds apartment, homeowners association and hotel pools to state rules: calcium hardness of at least 150 ppm and no more than 1,000, tested at least once every 10 days.
- pH
- 7.2–7.8
- Carbonate alkalinity
- 80–120 ppm
- Calcium hardness
- 200–400 ppm
- Cyanuric acid (stabilizer)
- 30–50 ppm
- Total dissolved solids
- Up to 1,500 ppm over the fill water
The council's ranges for a plastered pool. A fiberglass pool maker sets its own. Test your own pool.
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(830) 302-4112Removing scale from pool tile and finishes
Scale already on the tile comes off by hand, by blasting or with acid, and tile makers disagree on which of those their tile can take. Our pool tile cleaning page sets the methods side by side. Whichever is used, a pool chemical maker warns that scale usually comes back unless the water balance behind it is fixed.
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(830) 302-4112Hard water pool questions
How do you fix hard water in your pool?
Balance the water rather than fight the hardness. A pool maker says pH can affect calcium scaling more than calcium levels do, so it starts by lowering the pH. A pool chemical maker's method keeps the saturation index slightly negative while a scale-control product works, which it says generally takes 2 to 3 weeks.
How can I lower the hardness in my pool?
The council's answer for very high calcium or dissolved solids is to drain part or all of the water, refill and rebalance, which can take 7 to 10 days. In New Braunfels, the drought plan allows a drain for three things only, and high hardness isn't one: rainwater above the normal level, a hazardous pool part, or a leak. Ask New Braunfels Utilities first, and bear in mind that the refill water is hard too.
Does baking soda lower hardness in pool?
The council lists baking soda (sodium bicarbonate) as a way to raise total alkalinity: 1.5 pounds lifts the alkalinity of 10,000 gallons by 10 ppm. Higher alkalinity pushes water toward scale. The council's start-up card also says never to add baking soda and calcium chloride at the same time.
Does chlorine increase water hardness?
It depends on the kind. A fiberglass pool maker bans calcium hypochlorite (a powdered chlorine) on its gelcoat because it causes calcium scaling and cloudiness. Tri-chlor tablets (slow-dissolving chlorine tablets) bring cyanuric acid: about 55% of a 7-ounce tablet, the council says. It warns that 100 ppm or more of cyanuric acid may permanently damage a pool surface.
Talk through hard water and your pool finish
New Braunfels Quality Pool Resurfacing answers calls and estimate requests 24/7, and estimates are free. We'll talk through your water, the finish that suits it and the tile at the waterline.