How Water Softener Installation Works: Steps, Sizing and Cost

Do you need a water softener? Hardness levels to know

Hardness in the Valley is high. The City of Phoenix's 2025 water quality report lists total hardness of 10 to 17.6 grains per gallon. Chandler reports a citywide average of 16.5 grains per gallon. Mesa recommends that residents set softeners to 16 grains per gallon. A common scale calls anything over 10.5 grains per gallon very hard.

Hardness does not make water unsafe, so a softener is a comfort and home-protection choice. Homeowners usually install one because of:

• Scale on faucets, shower heads and glass doors
• Water heaters losing efficiency or making noise
• Spotty dishes and stiff laundry
• Wanting appliances and fixtures to last longer

Look up your city's numbers in our Phoenix water hardness guide or find your city on our water softener service areas page.

Water softener sizing worksheet (grain capacity math)

Grains per day = hardness (gpg) × people × gallons per person per day. Multiply by the days you want between regenerations to get the capacity the softener must deliver. University of Nebraska-Lincoln Extension says the right size depends on hardness, daily water use and peak flow rate.

1. Find your hardness in grains per gallon

   Use a test at your tap. Your city's report is a starting point; if it gives mg/L or ppm, divide by 17.1. Look up your city in our Phoenix water hardness guide.

2. Estimate daily water use

   Multiply the people in your home by gallons per person per day. The EPA's WaterSense program says each American uses an average of 82 gallons a day at home. Better: divide the gallons on your water bill by the days in the billing period.

3. Work out grains per day

   Hardness × daily gallons = the grains of hardness the softener must remove each day.

4. Choose days between regenerations

   A well-sized softener regenerates every few days rather than daily. Each regeneration uses water (UNL Extension puts it at roughly 50 gallons), so very frequent cycles waste salt and water.

5. Multiply for capacity

   Grains per day × days between regenerations = the capacity needed between regenerations. Ask each installer what capacity their unit actually delivers at the salt setting they plan, how much reserve they build in, and whether its flow rate suits your bathrooms.

Our arithmetic. Assumptions: the EPA's 82-gallon figure is total use at home, and the EPA says outdoor use averages more than 30 percent of household use. Outdoor lines are usually left unsoftened, so this overstates indoor use; your bill is the better number. The examples don't prescribe a product or size.

The same household needs about 60 percent more capacity at 16 gpg than at 10 gpg. That's why a quote sized to a city average can be wrong for your house, and why Valley homes at the hard end of their city's range often need a larger unit. Angi's Phoenix equipment prices by grain capacity are in our water softener cost guide.

Is softened water safe to drink?

Experts differ, so here are both views. Many households drink softened water, and the softening itself isn't covered by a drinking water health standard. But it does contain extra sodium or potassium, and University of Arizona Extension cautions that soft water may not be suitable for drinking because of its salty taste and elevated sodium or potassium. UNL Extension estimates about 8 mg/L of sodium is added for each grain per gallon of hardness removed. At 16 gpg, that works out to roughly 128 mg/L. People on a sodium-restricted diet should talk with their doctor.

UNL suggests keeping a cold-water line to the kitchen tap that bypasses the softener for drinking and cooking. Many Valley homeowners instead add an under-sink reverse osmosis system, which reduces sodium at that faucet. Potassium chloride is another option, though UNL notes it can cost more and may need more product to do the same work.

Who can install a water softener in Arizona? Licensing and brine rules

Arizona ROC license (R-54)

Arizona's Registrar of Contractors has a residential license classification for water conditioning equipment (R-54). It covers installing and repairing water conditioning equipment, exchange tanks and the indirect waste pipe that carries brine and rinse water to the point of disposal. Plumbing contractors are also licensed. Always check a company's license number at the Registrar of Contractors before you sign.

HOA rules, septic and brine discharge

There is no statewide ban on home water softeners in Arizona. Some HOAs and community rules may limit them, so check your CC&Rs. If your home is on a septic system, ask the installer how the brine rinse will be handled.

Water softener installation FAQs