Cleaning out a brine tank is a straightforward physical job that goes wrong mainly through impatience: emptying a tank still full of salt, or putting it back into service before the detergent is rinsed out. Working through it in order takes an afternoon at most, and it is worth combining with the small component checks that are only convenient while the unit is bypassed.
Prepare, then bypass
Let the salt run down over the preceding weeks rather than removing a full tank, which is heavy and wasteful. When the level is low, put the softener into bypass and confirm it with a nearby tap: you should still have water and it should feel hard. Unplug the control valve. Disconnect the brine line from the tank, noting how it was routed, and have a bucket, a scoop, a hose and mild detergent ready before anything comes apart.
Empty and wash
Scoop out remaining salt, then remove the brine well by lifting it clear, taking care not to snap the float assembly. Bail out the brine and the sludge at the bottom, which is insoluble residue from the salt and is the reason the job is being done. Wash the tank with warm water and a mild detergent, then rinse thoroughly, several times, because detergent left behind ends up in the brine and then in the resin. Wash the brine well and the float too.
Do the small parts while it is open
Pull the injector cap and rinse the nozzle and its screen, which catch salt fines and grit and are the most common single cause of a softener that has stopped drawing brine. Check the float slides freely and the safety overflow is clear. Inspect the brine line for splits and the fittings for looseness, because an air leak stops the draw as effectively as a blockage. These take minutes now and are awkward to reach at any other time.
Reassemble and prove it works
Refit the brine well, reconnect the brine line properly clamped, add clean pellets to about two thirds and no more, and add water to the tank if the manufacturer directs. Restore power, return the bypass to service slowly rather than snapping it across, and run a manual regeneration while watching and listening: you should hear the drain flow change through the stages and see the brine level fall during the draw. Our softener installation guide covers the bypass and drain connections.
Questions people ask about how to clean a water softener
How do I empty the tank without wasting salt?
Let the level run down over the preceding weeks, then clean when there is little left rather than removing a full tank.
What is the sludge at the bottom?
Insoluble residue from the salt, worse with rock salt, which eventually reaches the brine well and the injector.
What should I check while the tank is open?
The injector and its screen, the float and safety overflow, and the brine line for splits or loose fittings.
How do I confirm it works afterwards?
Run a manual regeneration and watch: the drain flow should change through the stages and the brine level should fall during the draw.