If you've had your pool resurfaced more than once and keep running into calcium buildup, scaling, or early surface failure — it's not bad luck. It's your water. San Antonio draws from the Edwards Aquifer, one of the most mineral-rich groundwater sources in Texas, and those minerals are silently destroying standard pool surfaces every day.
This guide covers what's in the water, what it does to pool surfaces, and which finishes actually hold up after years of exposure to Hill Country conditions.
What Is the Edwards Aquifer?
The Edwards Aquifer is a natural underground limestone reservoir that stretches across south-central Texas, fed by rainfall on the Hill Country's Balcones Escarpment. As water moves through the limestone rock, it dissolves calcium carbonate — which is why San Antonio's tap water carries unusually high levels of calcium and magnesium by the time it reaches your home.
- Calcium hardness: 250–350 ppm (national pool ideal is 200–400 ppm — SA consistently at the high end)
- Total alkalinity: 120–180 ppm
- pH at source: 7.5–8.2 (tends to run high)
- Total dissolved solids (TDS): 400–600 ppm
- Magnesium hardness: 40–70 ppm
When this water is added to a pool and then sits in the Texas heat — 90°F+ summers, intense UV — evaporation concentrates these minerals further. What started at 300 ppm calcium can climb to 500+ ppm within two seasons if you're only topping off and not draining.
How Hard Is San Antonio's Water? A Texas Comparison
San Antonio
Austin
Dallas
Houston
San Antonio consistently runs 2–3x harder than Houston, and noticeably harder than Austin. When pool contractors elsewhere talk about hard water problems, they're often describing water half as mineral-dense as what comes out of your tap here.
What Hard Water Does to Your Pool Surface
The damage happens in two opposite directions, sometimes alternating seasonally:
Calcium Scaling
When pH climbs above 7.8 and calcium is already high, calcium carbonate precipitates out of solution and bonds to the pool surface. The result: white, rough, crusty deposits that feel like sandpaper. Once this happens, only acid washing or mechanical removal fixes it — and acid washing shortens plaster life with every application.
Surface Etching
During phases where CO₂ is consumed rapidly (hot days, heavy bather loads), water turns corrosive. It leeches calcium out of the plaster matrix, leaving a rough, pitted, chalky surface. This is why San Antonio plaster jobs often look 10 years old by year 5 — the water is literally consuming them.
Shortened Surface Lifespan
National industry averages say plaster lasts 10–12 years. In San Antonio's Edwards Aquifer conditions, real-world performance is 6–9 years. That's a 30–40% shorter lifespan, which means you're paying for resurfacing significantly more often than homeowners in softer-water markets.
Which Pool Surfaces Hold Up to Edwards Aquifer Water
Standard White & Colored Plaster
Plaster is a mix of white cement, marble dust, and water. The cement matrix is naturally porous and reacts directly with dissolved calcium. In San Antonio conditions:
- Calcium scaling starts appearing within 2–4 years
- Rough, sandpaper texture develops as calcium deposits build
- Acid washing needed every 3–5 years, each time thinning the surface
- Full resurfacing required at 6–9 years vs 10–12 national average
- Cost savings at install ($1,500–$3,000 less than quartz) disappear when you're resurfacing 30% sooner
Quartz Aggregate (Quartzscapes, Diamond Brite, StoneScapes)
Quartz finishes blend crushed quartz crystals into the plaster matrix. Quartz is chemically inert — it doesn't react with calcium or carbonate ions the way plain cement does. In SA conditions:
- Dense, smooth surface doesn't give calcium rough pores to attach to
- Resists etching — inert quartz doesn't dissolve in corrosive water phases
- Easier water balance maintenance — less plaster chemistry interference
- Realistic lifespan of 12–18 years in SA (vs 6–9 for plaster)
- Cost-per-year often lower than plaster once you factor in the longer replacement cycle
For most SA homeowners, quartz is the right call — meaningful durability upgrade, not the highest upfront cost, and realistic for 15+ years with normal maintenance.
Pebble Tec & Pebble Sheen
Pebble finishes embed natural or artificial pebbles in a plaster matrix. The pebble surface is essentially impervious to calcium attack — calcium cannot bond to the smooth, non-porous pebble surface the way it bonds to plaster pores.
- 18–25 year lifespan with normal maintenance in SA conditions
- Near-zero calcium scaling on the pebble surface texture
- Dramatically reduced acid washing needs — often zero over the surface's full life
- Retains color far better than plaster (mineral-resistant pigmentation)
- Annualized cost-per-year is often lower than replastering every 7–8 years
If you're on your second or third set of plaster, pebble pays for itself — you're spending more per resurfacing cycle than a one-time upgrade costs spread over 20 years.
Surface Comparison at a Glance
| Surface | SA Lifespan | Hard Water Resistance | Cost (avg SA pool) | Annualized Cost* |
|---|---|---|---|---|
| White Plaster | 6–9 yrs | Poor | $4,000–$6,500 | ~$600–$850/yr |
| Colored Plaster | 7–10 yrs | Poor–Fair | $5,000–$7,500 | ~$600–$900/yr |
| Quartz Aggregate | 12–18 yrs | Good | $6,500–$9,500 | ~$430–$650/yr |
| Pebble Tec / Pebble Sheen | 18–25 yrs | Excellent | $7,500–$11,000 | ~$380–$540/yr |
| Glass Bead | 15–20 yrs | Very Good | $9,500–$13,500 | ~$540–$780/yr |
*Annualized cost = installed price ÷ midpoint lifespan. Does not include maintenance savings from less acid washing with harder surfaces.
Protecting Your Pool Between Resurfacings
Regardless of which surface you choose, these four practices make a significant difference in how long it lasts under SA water conditions:
Questions Alamo Heights, Stone Oak & Helotes Homeowners Ask Us
Can I use a water softener to protect my pool?
No. Water softeners use sodium ion exchange — adding softened water to a pool raises sodium levels, disrupts chlorine chemistry, and can cause corrosion. Softeners are for household plumbing, not pool fill water. The correct approach is surface selection + chemistry management.
Will SAWS water quality change?
Not significantly. The Edwards Aquifer's mineral content is geological — it doesn't meaningfully change year to year. SAWS does blend sources occasionally (Carrizo Aquifer, recycled water) but the overall hardness range stays consistent. Plan your surface choice around long-term SA water chemistry, not hoping for softer water.
My pool service company says my water balance is fine — why is my plaster still failing?
Standard water balance checks (pH, alkalinity, chlorine) don't directly measure calcium hardness or LSI. A pool can test "balanced" and still have calcium hardness at 400+ ppm, which slowly destroys plaster over years. Ask your service company to specifically test and report calcium hardness quarterly. Anything over 400 ppm is grounds for a partial drain.
How do I know if my pool needs resurfacing vs acid washing?
Rough texture, visible white/grey staining, or pitting that doesn't improve after acid washing means the surface is past its useful life. Acid washing helps scaling but doesn't rebuild a depleted surface. If you've acid-washed twice and the texture keeps coming back rough, it's time to resurface — and to choose a harder-water-resistant finish this time.
Related Resources
Best Pool Surface for San Antonio's Hard Water (2026 Comparison) Pool Resurfacing Cost in San Antonio How Much Does Pool Resurfacing Cost in San Antonio? Pool Resurfacing Cost Calculator — San Antonio Pool Resurfacing in Alamo Heights Pool Resurfacing in Stone Oak Pool Resurfacing in Helotes (Hill Country)Free In-Home Surface Consultation
We'll bring quartz and pebble finish samples to your home, assess your current surface, and give you an honest recommendation for SA's water conditions — with exact pricing on the spot. No pressure, no commitment required.
Call (726) 268-5597 Or request an estimate online →