Water Softener Hardness Setting

Step 1: Get a real hardness number

You have three ways to find it:

• On city water, your utility's annual water quality report usually lists hardness. Look for "hardness" or "total hardness," often given in mg/L or ppm.
• Test strips or a drop-count kit are cheap and good enough for setting a softener. Test raw water from a tap before the softener, such as an outdoor spigot.
• A lab test is the best option on a private well, since you'll want iron and manganese too. HomeGuide lists a hard water test at $130 to $200. Use a state-certified lab for anything beyond hardness, and see our hard water testing page for how to sample.

That covers people searching for a setting for Las Vegas, San Antonio or any other city too. Don't copy a number from a forum. Pull your own utility's report, since hardness can differ between wells and treatment plants in the same metro.

Step 2: Convert to grains per gallon

Most softeners want gpg. Morton gives the conversion as 1 gpg equals 17.1 mg/L or ppm. Divide mg/L by 17.1 to get gpg.

For a sense of scale, Penn State Extension calls water over 7 gpg hard and over 10.5 gpg very hard.

Step 3: Add for iron

Softeners can remove some dissolved (clear-water) iron, but iron uses up resin capacity, so the makers tell you to raise the hardness number to cover it. The amount varies by brand:

Whirlpool's own example is 20 gpg hardness with 2 ppm of iron, which means entering 30. Use the figure in your own manual, since the brands don't agree.

Iron above what the softener is built for needs its own treatment. Hellenbrand rates the H100 for up to 2 ppm of ferrous bicarbonate iron, and Whirlpool says its softener will not remove ferric or bacterial iron. EPA's non-enforceable secondary standard for iron is 0.3 mg/L. If you're above that by a lot, read iron in well water.

Step 4: Enter the setting

Every control head is a little different, but the pattern is the same: press a program or set button until the display shows hardness, change the number with the up and down arrows, then press program again to save.

On the Whirlpool WHES48, for example, you press PROGRAM until a flashing number and the word HARDNESS appear; the default shown is 25. Hellenbrand's controls default to 20 and accept 1 to 150 in one-grain steps. If your unit uses a dial or a set of grain-capacity and day settings instead, the manual will have a chart that matches hardness and household size to a setting.

Step 5: Check it after a week

After you change the number:

If water goes hard just before each regeneration, raise the setting a grain or two or check the regeneration schedule. Our page on how often a softener should regenerate shows how hardness, water use and capacity fit together.

Mistakes to avoid

• Setting it "high to be safe." Minnesota's health department says an overly high setting costs more to run and wastes water.
• Testing softened water instead of raw water. You'll get a near-zero reading and set the softener to nothing.
• Forgetting the iron allowance on a well.
• Ignoring the clock. On timer and meter models, a wrong time of day means regenerations happen while you're showering.
• Leaving the factory default. A default of 20 or 25 gpg is a placeholder, not your water.

When it's a pro job

Changing the setting is a homeowner job. Call a water treatment pro if the softener won't hold settings after a power outage, the display is blank, or the water stays hard after a correct setting and a manual regeneration. That points to a control, resin or salt problem; start with water softener repair.