Whole House Water Softeners in Oak Point

Oak Point’s water comes from Mustang Special Utility District, organized on October 1, 2002, out of the Mustang Water Supply Corporation; it has since absorbed the former Marilee Special Utility District, and its 2025 report lists water-quality test sites on Spinnaker Run in Oak Point. Mustang does not have one water. It pumps its own wells in the Trinity and Woodbine aquifers under Collin, Denton and Grayson counties, buys treated lake water from the Upper Trinity Regional Water District, and buys groundwater from the City of Sherman. Upper Trinity, created in 1989, treats Lewisville and Ray Roberts lake water at its Tom Taylor plant in Lewisville and sends Jim Chapman Lake water to its newer Tom Harpool plant in northeast Denton County. Mustang’s own newsletter puts the split in round numbers: about 60 percent of its supply is surface water and about 40 percent groundwater. Upper Trinity describes a joint Temple Dane pump station and a million gallon storage tank that it operates in partnership with Mustang to supply its northern service area, and the federal facility record places Mustang’s Temple Dane plant and pump station on FM 720, with five 2,000 gallon a minute pumps and a 2 million gallon ground tank.

The two sources sit at opposite ends of the hardness scale. The district’s 2025 report prints total hardness for its own well water at 4.773 ppm, in a range of 3.68 to 5.48, which is about as soft as water gets, under a third of a grain per gallon. The same table explains why: 222 ppm of sodium, 530 ppm of alkalinity and 734 ppm of total dissolved solids, with magnesium at less than half a part per million. Calcium, the other half of hardness, averaged 1.22 ppm in a range of 0.99 to 1.41 on page 9 of the same report, and an older line from 2016 on page 10 gives the well water’s hardness as calcium and magnesium at 5.24 ppm; the wells’ pH of 8.8 and 261.4 ppm of bicarbonate complete a very soft, alkaline profile. That is the signature of the deep sandstone aquifers under Denton County, where the water has traded its calcium and magnesium for sodium on the way down. Reservoir water is the reverse. It carries the calcium and magnesium it collects from the land it drains, which is why treated lake water across North Texas is generally described as moderately hard, and why a water heater on lake water scales while one on Mustang well water does not.

Mustang’s report prints no hardness figure for the Upper Trinity water or for the blend that reaches Oak Point, and the share of well and lake water changes with the season, with demand and with the pressure zone a street sits in. A home near the lake and a home on the U.S. 380 side can be drinking different water on the same day. So we do not have a number for the town, and will not guess one. A free water test gives you the number at your own tap; if it comes back under a grain, you are on the wells and a softener has little to do, and if it comes back at eight or nine, you are on the lake.

Sources: Mustang SUD 2025 Consumer Confidence Report · Mustang SUD Rate Order · Upper Trinity Regional Water District — Water Sources · Upper Trinity Regional Water District — History · Mustang SUD, In the Pipeline newsletter, Part One: Where Our Water Comes From · Upper Trinity Regional Water District: Water Treatment and Delivery · U.S. EPA Envirofacts SDWIS: water system facilities for TX0610036