Water Softener

A water softener is a whole-house unit that removes the calcium and magnesium that make water hard, exchanging them for sodium so the water stops leaving scale and soap scum.

Hard water carries dissolved calcium and magnesium that build up as crusty scale inside pipes, water heaters, and on faucets, and that fight with soap so it never lathers well. A softener treats this at the point where water enters the house. Water flows through a tank packed with resin beads that grab the hardness minerals and release sodium in their place, so what reaches the taps is soft.

A second tank, the brine tank, holds the salt. Periodically the unit runs a regeneration cycle: it flushes a strong salt solution through the resin, stripping off the collected hardness and recharging the beads for the next round. Modern metered softeners regenerate based on actual water use rather than a fixed clock, which saves salt and water. The result is longer-lasting appliances, easier cleaning, and softer skin and laundry.

Softeners are mechanical and do need upkeep. The salt has to be topped up, the brine tank can form a salt bridge that blocks regeneration, and the resin slowly loses capacity over many years. When a softener stops working, the first signs are usually scale returning and soap that will not lather.

Cost & troubleshooting guides
Related terms
Lines open 24/7

Talking to a contractor about this?

Run the project past a licensed plumbing pro first. Calls are answered around the clock and routed to a pro serving your area.

(855) 000-0000
More in Water Treatment
  • Reverse Osmosis (RO) : Reverse osmosis is a filtration method that forces water through a fine semipermeable membrane to strip out dissolved salts, minerals, and most contaminants, producing very pure drinking water.
  • Sediment Filter : A sediment filter is a mechanical filter that strains out sand, rust, silt, and other suspended particles before they reach fixtures or downstream treatment equipment.

← All plumbing terms

Call (855) 000-0000