If you moved to the DFW area from somewhere else and tried to maintain your pool the same way — you probably ran into problems fast.
That's because North Texas water is genuinely different from most of the country. It's not just "a little hard." It's some of the hardest municipal water in the United States, and it creates challenges that pool care guides written for other regions completely miss.
This isn't a generic water chemistry article. This is specifically about YOUR water, coming out of YOUR tap, filling YOUR pool in the Dallas-Fort Worth area.
What Comes Out of Your Tap
Before your pool water is "pool water," it's city water. And city water in DFW starts with some serious baggage.
Here's what we typically see when we test freshly filled pools across our service area:
| Parameter | DFW Tap Water (Typical) | Ideal Pool Range | The Gap |
|---|---|---|---|
| Calcium Hardness | 150-300+ ppm | 200-400 ppm | Often starts high, only goes up |
| Alkalinity | 120-200 ppm | 80-120 ppm | Already above target on day one |
| pH | 7.8-8.4 | 7.2-7.6 | Way too high from the start |
| TDS | 400-800 ppm | Under 1,500 ppm | Starts elevated, climbs with evaporation |
| CYA | 0 ppm | 30-50 ppm | You add this — but watch it |
Notice something? On the day you fill your pool, your water is already out of spec on alkalinity and pH. You're fighting an uphill battle from minute one.
The cities in our service area — Northlake, Argyle, Flower Mound, Trophy Club, Roanoke, Denton, Highland Village, Southlake — all draw from similar water sources (primarily Lake Lewisville, Lake Grapevine, and Trinity River Authority). The water quality varies slightly by city, but the pattern is consistent: high calcium, high alkalinity, high pH.
Why Hard Water Wrecks Pool Equipment
Calcium doesn't just sit in your water looking harmless. When conditions are right — and in DFW, conditions are almost always right — calcium precipitates out of solution and deposits on every surface it touches.
Your salt cell gets coated. Those white crusty deposits you see? That's calcium carbonate. It insulates the cell plates, making them work harder to produce chlorine, burning through the cell faster. A salt cell that should last 5-7 years might last 3-4 in DFW if you're not cleaning it regularly.
Your tile line gets that white scum. That's not "soap scum." It's calcium scale, and it bonds to tile like concrete. Once it hardens into calcium silicate (which happens when you ignore calcium carbonate long enough), even acid won't remove it — you need glass bead blasting. Our guide on tile cleaning and calcium removal covers the details.
Your heater exchanger scales up. Calcium deposits inside the heat exchanger reduce efficiency. You're burning more gas to heat the same amount of water. Eventually, the restricted flow triggers safety shutoffs.
Your plaster ages faster. Calcium deposits on plaster create a rough, uneven surface that grabs algae and stains. Pool surfaces that should last 10-15 years in soft water areas might need resurfacing in 7-10 in DFW.
The Alkalinity Problem Nobody Talks About
Most pool guides say "keep alkalinity at 80-120 ppm." Great advice. Except your DFW tap water comes in at 120-200 ppm. So you're already above target on day one, and alkalinity naturally rises with evaporation and chemical use.
Here's why this matters more than you think:
High alkalinity locks your pH high. Alkalinity is pH's bodyguard. It resists pH changes. That's normally a good thing. But when alkalinity is too high, it resists your INTENTIONAL pH changes too. You add acid to lower pH, the high alkalinity buffers it right back up. You feel like you're pouring money down the drain.
The column pour technique. This is something most pool care articles skip. To lower alkalinity without tanking your pH, you add muriatic acid in a slow, concentrated pour in one spot — right over the deepest area, pump off. The concentrated acid locally overwhelms the alkalinity buffer. You let it sit for 30 minutes, then run the pump to mix. Repeat as needed.
We have a full walkthrough: How to Lower Pool Alkalinity.
Our recommendation for DFW pools: Target alkalinity at 70-90 ppm instead of the textbook 80-120. This gives you room for the natural upward drift that our water conditions create. Your pH will be easier to control at this slightly lower alkalinity target.
The Evaporation Multiplier
DFW is hot. DFW is dry (relatively). DFW pools evaporate a LOT of water.
A typical DFW pool loses 1-2 inches of water per week during summer. That's 300-600 gallons. Every week. All summer.
Here's the critical thing: when water evaporates, everything dissolved in it stays behind. The calcium stays. The CYA stays. The salt stays. The TDS stays. Only the water leaves.
So every time you top off with more high-calcium DFW tap water, you're adding MORE calcium and minerals to an already concentrated pool. It's a one-way ratchet. Calcium only goes up.
This is why partial drain-and-refills are a normal part of pool ownership in DFW. Not a sign that something is wrong — just the physics of our climate and water supply.
Our recommendation: Plan for a 25-30% water replacement once a year, typically in early spring. Drain some out, fill back up with fresh water. This resets your calcium, CYA, and TDS levels. It's cheap insurance.
CYA: The Texas Sun Problem
Cyanuric acid (CYA) stabilizes chlorine against UV destruction. Without it, the Texas sun would burn through your chlorine in a couple hours.
But CYA accumulates. Every trichlor tablet you add puts more CYA in the water. It doesn't evaporate, it doesn't filter out, and the only way to remove it is draining water.
The DFW double whammy: Our intense sun means you need CYA (30-50 ppm is ideal). But our long swim season (April through October — sometimes March through November) means you're adding trichlor tablets for 7-8 months straight. CYA builds fast.
By August, many DFW pools that rely solely on tablets have CYA over 100 ppm. At that level, your chlorine is barely functional. You're adding more and more chlorine that does less and less. We see this constantly.
The fix:
- Use liquid chlorine (sodium hypochlorite) as your primary sanitizer — it adds zero CYA
- Use tablets only when you can't dose liquid (vacation, etc.)
- Test CYA monthly from May through September
- If CYA hits 80 ppm, stop tablets immediately and switch to liquid only
- Do a partial drain to dilute if it gets above 100
More details: How to Fix High CYA Levels and Liquid vs. Tablet Chlorine.
What We Actually Do Differently for DFW Pools
After servicing hundreds of pools across Northlake, Argyle, Flower Mound, Trophy Club, Denton, and the surrounding cities, we've developed a DFW-specific approach. Here's the short version:
Chemical targets adjusted for our water:
- Alkalinity: 70-90 ppm (not the textbook 80-120)
- pH: 7.2-7.4 (we keep it on the lower end of acceptable because it wants to drift up)
- Calcium hardness: We monitor it but focus on preventing precipitation rather than targeting a number
- CYA: 30-40 ppm (lower target because our sun is intense and we don't want to overshoot)
We use liquid chlorine as the primary sanitizer. No CYA problems. Precise dosing. We can adjust every visit based on actual test results.
We use sequestering agents proactively. A small dose of phosphonic acid-based sequestrant keeps calcium and metals in solution instead of depositing on your surfaces and equipment. Cheap prevention.
We push filter cleaning frequency. DFW's high mineral content clogs filters faster than soft-water areas. We clean filters more often than the national average recommends.
We plan for annual water replacement. It's part of the maintenance cycle here. Not an emergency — just smart management.
Do It Yourself? Know Your Water First.
If you maintain your own pool, the single most important thing you can do is get a baseline water test from a local professional. Not just a strip test from the hardware store — a full panel including calcium hardness, CYA, TDS, phosphates, and metals.
Bring a water sample to our Northlake store and we'll test it for free. Seriously. We'd rather you maintain your pool properly as a DIY-er than do it wrong and end up with a $3,000 resurfacing job.
Pick up test kits, chemicals, and supplies calibrated for what DFW water actually needs. Or if you'd rather have us handle it — our weekly service starts at $165/month, chemicals included.
Contact us or call (469) 455-1054. We'll talk you through your water situation and figure out the best approach for your specific pool.
