Test first, then decide
Hardness varies from street to street and from source to source. A softener sized without a test is a guess. A test strip from a hardware store gives a rough reading, and a lab test gives a precise one.
Your water supplier publishes a water quality report. Use that for background, and test a tap in your own house for the number that matters, because plumbing in the house can add to what arrives.
What a softener does and does not do
| It does | It does not |
|---|---|
| Remove calcium and magnesium that cause scale | Make water safe if it has a contamination problem |
| Reduce buildup in heaters, fixtures and pipes | Remove chlorine taste or odors |
| Help soap lather and cut cleaning time | Filter lead. A certified filter does that |
| Add a small amount of sodium to the water | Fix low water pressure |
A softener swaps hardness minerals for sodium or potassium. People on low sodium diets should ask about the numbers, and a separate drinking water tap can be installed.
Where it goes and what it needs
A softener sits on the main water line, usually in a basement near the water heater. It needs a drain for the regeneration water, a nearby electrical outlet and room for a salt tank.
Plumbers install a bypass so the unit can be isolated for service. In a house with an older water heater, softened water often helps by slowing scale buildup in the tank.
Upkeep
Check the salt every month or two and keep the brine tank clean. Most units regenerate on a schedule or by water use, and settings can be adjusted when the household changes. A unit that stops softening, or uses far more salt than before, needs service.
Salt, sodium and discharge
A softener recharges with salt brine and flushes the wash water to a drain. That water is salty, which some septic systems and some municipalities treat differently. Ask what applies at your address.
Potassium chloride can replace salt for people who want to avoid added sodium. It costs more and works slightly differently, and a plumber can set the unit up for either.
How capacity and regeneration fit together
A softener's capacity is rated in grains of hardness it can remove before it must regenerate. For example, a house using 250 gallons a day with water at 10 grains per gallon asks for 2,500 grains daily, so a 24,000 grain unit would regenerate roughly every nine to ten days.
A unit that is too small regenerates constantly and wastes salt. One that is far too large can sit for long periods between cycles. Sizing starts with a water test and an honest count of the household.