How Often a Water Softener Should Regenerate

The short answer

There is no single correct schedule, but the target most sizing advice works toward is about once a week. A unit that runs out of capacity about every seven days can use an efficient salt setting and still keep up.

The owned-store guides give a wider spread. One SoftPro page says regeneration typically happens every 2 to 3 days, another SoftPro page says every 3 to 5 days, and Quality Water Treatment says every 4 to 7 days for a two-person home. Penn State Extension's worked example (below) lands at 6 to 7 days.

A metered (demand) valve, such as the Fleck 5600SXT set to a meter control type, decides for itself by counting gallons, so the interval moves with how much water you use. A timer valve regenerates on fixed days whatever you use, so you have to pick the interval yourself. The settings guide explains which numbers on the valve control this.

Working out your interval

You need three numbers: your hardness in grains per gallon (gpg), your daily water use, and the usable capacity of the softener in grains.

1. Find your hardness. Use a test result, not a guess. If your report gives mg/L or ppm, divide by 17.1 to get gpg; SoftPro's Elite install guide says to round up. The hardness testing guide covers strips, drop kits and lab tests.
2. Estimate daily grains. Multiply people by about 75 gallons a day, then by hardness. If you have dissolved (ferrous) iron, follow your softener's manual; SoftPro's Elite guide, for example, raises hardness by 3 gpg where iron runs 2 to 3 ppm.
3. Divide capacity by daily grains. The answer is the number of days between regenerations.

Penn State Extension uses exactly this method: a 20,000-grain unit in a home of 4 people using 75 gallons each at 10 gpg removes 3,000 grains a day, so it should regenerate every 6 to 7 days.

Capacity is the part people get wrong. Rated capacity is measured at the maximum salt dose; at an efficient setting the same tank delivers less. Pentair's 5600SXT manual (4005293 Rev B) lists 31,100 grains at 9 lb of salt for a 1.0 cu ft unit, 46,600 at 13.5 lb for 1.5 cu ft and 62,200 at 18 lb for 2.0 cu ft. The Fleck 5600SXT service manual (42684 Rev B) says the control works out its capacity in gallons as unit capacity divided by feedwater hardness, minus the reserve.

On a metered valve the reserve and the day override also shape the schedule. Pentair says the safety factor can be 0 to 50% of capacity, and the day override (DO) is the maximum number of days between regenerations, from Off to 99. Quality Water Treatment's 5600SXT install guide programs DO at 14 and a 15% safety factor. The Fleck 5600SXT programming guide walks through each screen.

Too often

A softener that regenerates every day or two in a small household is usually telling you a setting is wrong. Quality Water Treatment lists these causes of high salt use: hardness set incorrectly, more water use than before, a damaged resin tank, salt bridges or mushy salt, a blocked brine valve, low pressure and brine overflow. Its fix is to set hardness from a real test, then check regeneration frequency and the brine level. SoftPro's troubleshooting page says a unit that regenerates too often points to a control valve or settings issue.

The Fleck service manual (42684 Rev B) gives two causes for using too much salt: an improper salt setting, or excess water in the brine tank. The too-much-salt guide goes through each check.

Not often enough

Long gaps are fine only if the water stays soft. If hard water shows up and the salt level barely moves, the softener is either not regenerating or not drawing brine. The Fleck manual (42684 Rev B) lists these causes of failing to regenerate: power interrupted (check the fuse, plug and switch), a defective timer, or a power failure that needs the time of day reset.

Other common causes:

• Hardness set too low or capacity set too high. The meter thinks more soft water is left than there is.
• Day override off on a metered valve. With DO off, a low-use home can go weeks between cycles. Quality Water Treatment uses 14 days as a backstop.
• Iron in the water. Quality Water Treatment's Fleck guide sets DO to 7 for 2 to 3 ppm of iron and reduces it by a day if staining continues; higher iron needs an iron filter.
• Salt not dissolving. A bridge means the valve regenerates but the resin is not recharged. See the salt not going down guide.

If you are not sure regeneration is happening at all, the regeneration guide explains what each step of a cycle should do.

Common questions

Related guides

• SettingsWater softener settings explained
• SettingsHow regeneration works
• FixHow to reset a water softener