How to Clean a Brine Tank

When it needs cleaning

The brine tank is the shorter tank that holds salt and water. Over time, dirt from salt bags and insoluble material settle on the bottom, and salt can turn into a soft sludge called mushing. Both stop the softener making strong brine.

Inspect the tank once a year, ideally when the salt is low. Clean it when you see sludge, dirt or a crust on the bottom. Pentair's 5600SXT manual recommends a full empty-out and wash roughly every three years even when nothing looks wrong. Clean sooner if:

• The salt level has not dropped for weeks and breaking the crust does not help (see salt bridge).
• There is a layer of mush or sludge at the bottom. SoftPro says mushing means emptying and cleaning the whole tank.
• The tank smells. SoftPro links a rotten-egg odor to bacteria in stagnant brine; our softener smell guide covers the causes.
• Water is standing high in the tank; check the brine tank full of water guide first, since that is usually a blockage, not dirt.

What you need

• A bucket, a wet/dry vacuum or a length of hose to siphon brine
• A scoop or small plastic container for old salt
• Warm water, dish soap and a non-abrasive brush (QWT)
• Plain, unscented household bleach and a measuring cup
• Rubber gloves and eye protection
• Fresh pellet or solar-crystal salt to refill

If the bottom of your tank has a salt grid, it lifts out for cleaning. QWT sells an 18 inch round brine grid with legs (BG184) (sold by Quality Water Treatment, our store) from $59.00 (October 2026), a raised platform that sits in the bottom of a round tank under the salt. Measure your tank before ordering, as grids are sized to the tank.

Cleaning steps

These steps follow Quality Water Treatment's cleaning guide; SoftPro's guide uses the same bleach dose and soak time.

1. Bypass the softener. Turn the bypass to the bypass position so the house still has water. Our bypass valve guide shows each type.
2. Turn off and unplug the control valve. This stops a regeneration starting while the tank is empty.
3. Disconnect the lines. Pull the brine line from the brine well fitting and the overflow tube from the side of the tank. Note how they attach.
4. Drain the brine. Siphon, scoop or vacuum out the water. QWT says to dispose of it away from plants, because salty water harms them.
5. Remove the old salt. Scoop out loose salt and any sludge from the bottom. Lift out the brine well and grid if they come free.
6. Scrub the tank. Wash the inside with warm, soapy water and a non-abrasive brush. Clean the brine well and grid the same way, then rinse out all soap before any bleach goes in, and never mix bleach with ammonia, acids or other cleaners.
7. Sanitize. Mix 1/4 cup of bleach in 2 to 3 gallons of water, slosh it over the inside walls and bottom, and let it stand for 15 minutes. Scrub again.
8. Rinse thoroughly. Rinse until no soap or bleach smell remains, and drain the rinse water.

Do not use vinegar inside the brine tank. QWT allows diluted vinegar only for small parts you have removed from the tank.

Cleaning the tank does not sanitize the resin. If you are dealing with odor or bacteria, follow up with the full sanitizing procedure, which runs bleach through the resin during a regeneration.

Refilling and restarting

1. Reassemble. Refit the grid and brine well, then reconnect the brine line and overflow tube. Check the float in the brine well moves freely.
2. Add water. QWT's cleaning steps say to add at least 5 gallons of fresh water before the salt. Some valves refill the tank themselves on a timed fill; on a Fleck SXT the refill amount is set by the brine fill (BF) time. Your manual is the final word.
3. Add salt. SoftPro suggests at least two 50-lb bags after cleaning. Keep the salt above the water line and roughly one-quarter to one-half full. Use pellets or solar crystals, not rock salt.
4. Plug in and return to service. Plug the valve back in, check the time of day, and turn the bypass back to service slowly.
5. Check it draws salt. Over the next few weeks the salt level should drop. SoftPro says salt that never moves, together with hard water, points to a regeneration problem.

If the old tank is cracked or the float assembly is worn out, replacement is often simpler than repair. QWT sells a round 18x33 brine tank (BT1833R B2310) (sold by Quality Water Treatment, our store) from $149.00 (October 2026); the store lists it with a cover, a 4-inch brine well, a brine overflow, 3/8-inch by 4-foot tubing and a Fleck 2310 safety valve, with a 375 lb capacity. Check your softener's manual for the right size before buying.

Related guides

• MaintainThe full softener maintenance schedule
• MaintainHow much salt to add after cleaning
• FixWhen the salt level never drops
• SettingsSoftener parts explained

Common questions