Texas Soft Water Guide

Frisco, Plano and McKinney water hardness (NTMWD)

Rowlett Creek winding through trees in Oak Point Park, Plano, Texas
Photo: Jackilometresan / Wikimedia Commons, CC0 1.0

Last reviewed: October 24, 2026.

Most homes in Frisco, Plano, McKinney and Allen get water that was treated by the North Texas Municipal Water District (NTMWD) and then delivered by the city. So the hardness figure that matters for most of Collin County comes from one place: NTMWD's annual water quality report. This guide walks through the 2025 numbers, what they mean for a softener decision, and how to size one if you go ahead.

How hard is the water?

NTMWD's 2025 Water Quality Report lists total hardness (as calcium carbonate) by treatment plant:

NTMWD plantTotal hardness, 2025About (gpg)USGS class
Wylie (Lavon Lake water)96.0–200 ppm5.6–11.7Moderately hard to very hard
Leonard (Bois d'Arc Lake water)96.0–144 ppm5.6–8.4Moderately hard to hard
Tawakoni (Lake Tawakoni water)60.0–249 ppm3.5–14.5Soft to very hard

The grains-per-gallon figures are our conversions using the divisor NTMWD itself gives customers: "divide the total hardness (mg/L) by 17.12." The USGS classes are from its hardness scale (61–120 mg/L moderately hard, 121–180 hard, over 180 very hard).

NTMWD describes its treated water as "moderately hard" and says that is "primarily due to the minerals found in Lavon Lake." It also notes these minerals "pose no harm to human health or safety" but can cause spots on dishes and lime scale on fixtures. Hardness is a nuisance and appliance question, not a safety one.

For comparison, that's harder than Austin Water's average of about 5.4 gpg and well below San Antonio's 15–20 gpg. See the full Texas water hardness by city table.

Which plant serves Frisco, Plano and McKinney?

According to the 2025 report, NTMWD's member cities and customers (except Bonham) were served by the Wylie plant. Some areas also receive water from the newer Leonard plant, and the report lists the City of Allen, City of Frisco, City of McKinney, City of Plano, Town of Prosper, Town of Fairview, Town of Little Elm, City of Melissa and City of Princeton among them, along with several rural utilities such as North Collin SUD and Milligan WSC.

In practice that means a home in these cities may get Wylie water, Leonard water, or a blend, and the mix can change. If you're sizing a softener, plan for the higher Wylie number (up to about 11.7 gpg) unless a test at your tap shows otherwise.

The Tawakoni plant mainly serves areas to the east, including Forney, Terrell, Kaufman and Crandall, according to the same report. Those homes saw the widest range in 2025, up to 249 ppm.

Plano's own 2025 water quality report reprints the same Wylie and Leonard tables. Your city's report will usually do the same, so it's a good place to confirm the numbers. Our guide to reading a Texas water quality report shows where to find the hardness row.

Chloramine: a filter question, not a softener question

NTMWD disinfects with chloramines. The 2025 report shows a Wylie plant average of 3.19 ppm and a Leonard plant average of 3.26 ppm, compared with a maximum residual disinfectant level of 4.0 ppm (which applies to the running annual average).

If your main complaint is taste or smell, a softener won't fix it. That's a job for catalytic carbon or reverse osmosis, covered in our Texas filtration guide.

Do you need a softener in Frisco, Plano or McKinney?

At roughly 5.6 to 11.7 gpg, this is the in-between zone. Many households live with it fine; others find the spotting and scale annoying enough to soften.

A softener is probably optional if:

A softener is worth a serious look if:

Sizing a softener for NTMWD water

A common rule of thumb assumes about 75 gallons per person per day indoors; your water bill gives the real number. Size for the high end of your plant's range.

Example, family of four on Wylie water: 11.7 gpg × 4 people × 75 gallons = about 3,510 grains per day, or about 24,600 grains per week. A softener rated to cover that at an efficient salt setting, with regeneration roughly once a week, fits. Headline capacities like "32,000 grain" are usually at maximum salt, and efficient settings deliver less, so check the manufacturer's capacity table.

The Pacific Northwest National Laboratory's Building America Solution Center says an efficiency rating under NSF/ANSI 44 or WQA S-100 requires demand-initiated regeneration, at least 3,350 grains removed per pound of salt, and no more than 5.0 gallons of water per 1,000 grains removed. At moderate hardness like this, a demand-initiated unit avoids wasting salt on regenerations you don't need.

Our SoftPro softener guide for Texas homes matches models to hardness levels like these. That guide contains affiliate links.

Salt-free conditioners

University of Nebraska–Lincoln Extension says salt-free devices "do not remove the hardness"; they are descalers. Template-assisted crystallization (TAC) turns hardness into tiny crystals that are less likely to stick. The same guide notes "few conclusive studies confirm the efficiency of these devices for residential use." At moderate hardness, some households try TAC for scale control, but if you want soft-feeling water and spot-free glass, only ion exchange (a salt-based softener) actually removes the calcium and magnesium.

Bottom line

NTMWD water in Frisco, Plano, McKinney and Allen ran about 5.6 to 11.7 gpg in 2025 depending on the plant. That makes a softener a reasonable comfort and scale-control choice, and a stronger case if you have a tankless heater or live on the Tawakoni side. Chloramine taste is a separate, filtration fix.

Sources

Related: Round Rock and Williamson County hard water · do you need a softener in Austin? · buying a home with an existing softener.

Information only; not plumbing or health advice. For water quality questions, contact your utility.