Park plant and Southside plant water: 309 to 320 mg/L

Last reviewed: September 12, 2026

That is roughly 19 grains per gallon. The USGS scale calls anything above 181 mg/L very hard, so this is not a borderline case. It is nearly double the 176 to 178 mg/L the city reports for water from Lake Georgetown and the Southlake plant.

If you moved here from the other side of town and your old house never seemed to have a problem, this is why.

What 19 grains does in a house

Scale builds fast. Aerators and shower heads crust over, glass doors film up quickly after cleaning, water heaters collect sediment faster, and a tankless unit without protection is on a clock.

At this level, a softener is usually the right call rather than a luxury. That is not a sales line. It is what the number says.

The sizing math, shown

Grains per day is your hardness in grains per gallon times the number of people times 75 gallons per person per day.

Capacity needed between regenerations is grains per day times the number of days you want between regenerations, which is typically 3 to 4.

Four people at 19 grains per gallon: 19 times 4 times 75 equals 5,700 grains per day. That is 17,100 grains at 3 days, or 22,800 grains at 4 days.

Two people at 19 grains per gallon: 2,850 grains per day, which is 11,400 grains at 4 days.

We use the high end of the published band on purpose.

The undersizing trap

Two things get people here.

First, the grain rating printed on a unit assumes a heavy salt dose. Run it at a more efficient salt setting, which is what most installers program, and the usable capacity is lower than the sticker. If your math lands right at the edge of a unit's rating, you are already undersized in practice.

Second, an undersized unit does not fail loudly. It just regenerates more often than it was designed to. You pay for that in salt, in water down the drain, and in resin that wears out years early.

Going much larger than the math is not free either. A unit so oversized that it sits a week or more between regenerations is its own problem. The point is to land the math deliberately, not to let the number be picked for you.

Chloramines shorten resin life here too

Georgetown typically uses chloramines as its disinfectant, and the city describes periodic conversions to free chlorine. Both are hard on ion exchange resin over time, and a standard carbon prefilter rated for chlorine is not the same thing as one rated for chloramines. More detail on that here.

Eight questions to ask before you sign

1. What hardness number did you use to size this, and what is your source for it.
2. What is the grain capacity of the unit, and how many days between regenerations does that give my household.
3. Is the control valve a serviceable, widely available family such as Clack or Fleck, or is it proprietary to your company.
4. If I call a different plumber in five years, can they get parts for this valve.
5. Is there a prefilter included, and is it rated for chloramines rather than chlorine.
6. What is the salt use per month at this size, and what is the water use per regeneration.
7. Who is doing the install, what license do they hold, and what is the license number.
8. What is the total price in writing, with no financing term attached, and what is the warranty on the valve and the tank separately.

Next steps

The $79 spec runs your numbers, prints the formula, and gives you the checklist in a form you can hand to a contractor.

Our plumbing listings are verified against the Texas State Board of Plumbing Examiners before they go up, and nobody pays to be on the list.