Arlington Water Is Moderate — Here's What It Costs You Each Year

Why Is Arlington Water So Moderate?

Arlington sits right in the middle of the hardness scale at 5.5 GPG (94 ppm), and the reason has everything to do with where the water actually comes from. This isn’t a groundwater town. Arlington Water Utilities buys its supply from the Tarrant Regional Water District, which pulls surface water from four reservoirs: Cedar Creek, Richland-Chambers, Lake Arlington, and Lake Benbrook. That distinction matters, because surface water and groundwater behave very differently when it comes to hardness.

Groundwater picks up calcium and magnesium as it slowly filters through limestone and dolomite aquifers underground. That’s why well-water towns in Texas often see 15, 20, even 30 GPG. Arlington doesn’t have that problem. The water here comes from reservoirs fed by rivers and creeks draining the surrounding watershed, and that water simply hasn’t spent decades soaking through mineral-rich rock. It flows over the surface, picks up some dissolved minerals along the way, but nowhere near what a deep aquifer would contribute.

Cedar Creek and Richland-Chambers are the big players in the TRWD system, and both sit in the East Texas region where the geology leans toward clay-rich soils and sandstone rather than thick limestone beds. Rainwater runs off into these reservoirs relatively quickly, carrying less dissolved calcium and magnesium than water that’s been underground for years. Lake Arlington and Lake Benbrook, the two smaller sources closer to home, follow the same pattern. They’re surface impoundments on creeks that drain the local rolling terrain, and their water chemistry reflects that short contact time with the soil.

That’s the whole story behind the moderate number. At 5.5 GPG, Arlington water is classified as hard by USGS standards (anything above 7 GPG is “hard,” and above 10.5 is “very hard”), but it’s nowhere near the mineral load you’d see in a limestone-aquifer city. The reservoirs do the heavy lifting. They dilute whatever hardness the local creeks contribute, and the result is water that’s noticeably harder than pure rainwater but a long way from the scale-builder that plagues so much of North Texas.

One thing worth understanding: the blend changes. TRWD shifts between reservoirs depending on the season, drought conditions, and demand. So the exact hardness at your tap can drift a little month to month. The 5.5 GPG figure is a solid average, but don’t be surprised if a water bill shows a slightly different number during a dry summer when the mix tilts toward one reservoir or another.

How Arlington Compares to Nearby Cities

Arlington’s moderate hardness puts it in a genuinely good spot relative to its neighbors, and the reason is simple: it’s not drawing from the same underground sources that make other parts of the metroplex so hard.

Fort Worth, for instance, also pulls from TRWD surface reservoirs, so its water profile is broadly similar to Arlington’s. Both cities rely on the same regional system, and both avoid the heavy mineral loads that come from groundwater. If you’ve lived in both places, you’ve probably noticed the water feels comparable at the tap.

The bigger contrast comes when you look at cities to the south and west that depend on the Trinity Aquifer or other well fields. Those communities routinely deal with hardness levels that dwarf Arlington’s 5.5 GPG. Water that’s spent years moving through limestone formations picks up calcium and magnesium far more aggressively than anything flowing out of Cedar Creek Reservoir. So while Arlington residents might notice a little scale on showerheads or need a bit more soap in the washing machine, their counterparts in aquifer-supplied towns are fighting a much tougher battle.

That difference shows up in real, practical ways. According to the WQA and Battelle Memorial Institute’s 2010 detergent study, soft water can cut laundry detergent use by up to 50% and dish soap by up to 70% compared to hard water. Arlington’s moderate water sits somewhere in the middle of that spectrum. You’re not getting the full savings of a soft-water home, but you’re also not wasting detergent the way a 15-GPG household does.

The same logic applies to water heaters. Battelle and the Water Quality Research Foundation found that gas water heaters lose about 4% efficiency per 5 GPG of hardness for a typical 50-gallon-per-day household. Arlington’s 5.5 GPG puts it right at that first efficiency hit, and the DOE notes that just a quarter-inch of scale can cut water-heater efficiency by up to 40%. At Arlington’s level, scale builds slower than in hard-water cities, but it still builds. The WQA’s industry estimate ties hard water to higher energy, appliance-wear, and cleaning costs overall, and that figure scales with your actual hardness. Arlington’s moderate number means those costs are real but modest, and the on-page calculator will show you exactly where you land.

How does Arlington stack up against the rest of Texas? It's moderate at 5.5 GPG — Midland, The Woodlands, and Brownsville sit nearby with different numbers. See the full hardest-water ranking for context.

See where Arlington sits on the Texas water hardness map →

Want the broader explainer on what hardness actually is and how it behaves? Read hard water vs. soft water, explained.