What are the benefits of a whole-house water softener?

Four benefits show up in the studies. None is a promise for your house, but each is measured.

• Less scale in water heaters. Battelle ran accelerated scaling tests for the WQRF. Gas storage heaters on unsoftened water dropped from 70.4 percent efficiency to 67.4 percent at two years of equivalent field service. Tankless gas heaters on unsoftened water "had to be delimed at 1.6 years of equivalent field service." By then their efficiency had fallen from 80 percent to 72 percent. The gas storage heaters on soft water built up "about 7 gm/yr" of scale. The ones on unsoftened water built up "about 528 gm/yr."
• Cleaner fixtures. Low-flow showerheads on unsoftened water "clogged after an average of 3,203 gallons of water flow through them." Showerheads on softened water "made it through the testing without any problems." Low-flow faucets on unsoftened water clogged after the equivalent of 19 days of water flow. The test speeds up scaling, so read this as a comparison, not a forecast.
• Less detergent. The WQRF laundry study found that the wash still came out better in softened water when it used half the detergent and cold water. The summary says so directly: "even when 50% of the detergent is used at a lower temperature of 60ºF instead of 100ºF, the washing yielded improved results when the softened water was used as compared to when hard water was used." The dishwasher study saw "detergent savings up to 70%." It also found that "hardness reduction was ~6 times more effective at reducing spotting" than adding detergent. The tests used water at 0, 15 and 30 grains per gallon. Phoenix water runs 10 to 17.6 grains per gallon, so the 15-grain point is the closest match.
• Less soap film. Penn State Extension says "hard water leaves scales on pots, soap films on skin, and detergent curds in the washing machine." Soft water "not only eliminates these nuisances but also protects appliances and saves cleaning time."

A softener has three limits worth knowing before you buy one.

• It does not purify the water. Penn State says the idea of softening as "a purifying, cleansing or conditioning process" comes largely from "exaggerated advertising." It adds that softening "simply removes hardness minerals and eliminates problems that are a nuisance and not a threat to human health." For drinking-water quality, see our page on reverse osmosis versus a water softener.
• It has not been shown to help eczema. A randomised trial followed 336 children with moderate to severe eczema in hard-water areas. It found that "water softeners provided no additional benefit to usual care in this study population." Our page on whether soft water is better for your skin covers what the trial did and did not test.
• It is not always right for the water heater. For electric storage heaters, PNNL says "artificial water softening is generally not recommended from an equipment maintenance perspective." For gas equipment, scale in extremely hard water "may justify" a softener. For tankless heaters, softening "may be required in most hard water conditions." PNNL also says soft water "corrodes anode rods," so a tank heater on softened water needs its anode checked. See whether salt softeners damage a water heater.

### What it costs

Beyond the limits above, a softener has running costs of its own.

Nebraska Extension puts the sodium addition at "about 8 mg/L for each grain per gallon (gpg) of hardness." That means softened Phoenix water carries roughly 80 to 140 mg/L more sodium than before. Our page on whether softeners add sodium to Phoenix tap water shows what that means per day. A softener also uses water and salt at every regeneration. The EPA WaterSense fact sheet says a typical unit uses 20 to 70 gallons of water per cycle. In the Valley it adds salt to the sewer system too. Our pages on choosing the right size softener and whether softeners work with Arizona hard water cover sizing, efficiency and the wastewater side.

A whole-house softener treats every fixture, but it does not have to. Penn State says "showers, sinks, and laundry hookups probably should be softened; toilets, outside spigots, and basement sinks can be bypassed." It also says softening systems can be adapted "for mixing softened and unsoftened water to produce a lower hardness level." That trims salt use and keeps sodium off the yard, since Nebraska Extension advises against repeatedly watering plants, lawns or gardens with softened water. Our page on where the bypass valve is and how to use it shows how those bypasses work.

Two limits apply to the numbers above. First, the WQRF summaries describe controlled tests with set hardness levels and accelerated scaling, so they show direction and size, not your exact savings. Second, they do not weigh the maintenance side of a softener, such as salt, resin and service. Penn State also points out that if you own a septic system, regeneration adds load to the drainfield, at about 50 gallons of water per cycle. A fair answer to "is it worth it" counts both columns. That is why a hardness test, a look at the water heater and a sizing check come before any purchase.

Match the benefit to your own situation. Use this short list.

1. 1Start with your number. The city's 2025 report lists hardness of 172 to 302 ppm, or 10 to 17.6 grains per gallon. Penn State calls anything above 10.5 grains "very hard." A hardness test strip or an independent lab test tells you what your own tap reads.
2. 2Look at your water heater. A tankless or gas tank heater gains the most from softening. An electric tank heater gains the least, going by the PNNL findings above.
3. 3Look at your fixtures. Crusty showerheads, spotted glassware and clogged aerators are the signs that scale is already costing you time and parts.
4. 4Count the trade-offs. Salt, sodium, water use and sewer salt all come with the unit. If anyone in the house is on a sodium limit, read our page on using potassium instead of salt and ask a doctor.
5. 5Do not buy it for skin or drinking water. The evidence does not support the first, and reverse osmosis is the better tool for the second.

Before you hire anyone, check your city's permit rule. Scottsdale, for example, lists plumbing for a water softener as work that needs a Minimum Plumbing Permit, as explained in does Scottsdale require a permit for a softener or repipe.

HQ Plumbing & Air is licensed and insured. We can test your hardness, look at your water heater and fixtures, and tell you whether a softener is worth it for your house. We offer free estimates and upfront pricing.

For the smaller shower head cartridges sold as softeners, see whether a shower head water softener helps hair and skin.

Spotted shower glass is another sign; removing hard water stains from glass shower doors covers the cleanup and prevention.