The short answer
A salt bridge is a hard crust that forms over a hollow in the brine tank, so the valve draws plain water instead of brine; break it up and keep the salt level lower.
Signs
- The salt level never seems to drop.
- Hard water returns even though there's plenty of salt.
- A broom handle hits a crust with empty space below.
Fixing it
- Put the softener in bypass.
- Tap the crust apart with a broom handle; don't strike the tank walls.
- Remove loose chunks, then run a manual regeneration.
Preventing it
Humidity and overfilling cause bridges. Keep the tank half to two-thirds full and use pellets such as Morton 1499 25 lb Softener Salt Pellets, Diamond Crystal Bright & Soft Softener Salt Pellets.
Products mentioned
Questions readers ask
What causes salt bridging?
Humidity and temperature changes harden the top layer while salt below dissolves away.
Do pellets bridge less than crystals?
Bridging depends mostly on humidity and fill level; clean pellets leave less residue at the bottom.