Tablet, block or granular: which salt does your softener need?

A water softener uses salt to clean its resin, so the salt you put in matters. The first rule is simple: use what your manufacturer specifies. Some softeners only accept one type, and the wrong one can stop the softener working properly.

Tablet salt

Tablets are the most common choice for domestic softeners. They are compressed, high purity salt shaped like large pills, usually sold in 10kg or 25kg bags. They dissolve slowly and evenly, and they leave little residue when they are good quality.

Tablet salt suits most cabinet softeners with a salt tank that you pour into. If your manual just says “salt”, it usually means tablets, but do check.

Block salt

Blocks are large compressed bricks, typically around 4kg to 8kg each. They are designed for particular softeners, which have a compartment shaped to hold them. If yours is one of these, tablets will not do the job.

Blocks are clean and easy to handle, because you drop in a new block rather than lifting a heavy bag. They do tend to cost more per kilo.

Granular salt

Granular salt is a coarser, loose salt. It is used in some older softeners and in commercial equipment. It dissolves quickly, but in a machine not designed for it, it can clump and form a crust. It is best kept for the equipment it was made for.

Why purity matters

Softener salt should be high purity, made for the purpose. Do not use cooking salt, rock salt or de-icing salt. They can contain impurities and additives that leave sludge in the tank and may damage the resin or valve.

Keeping the tank healthy

• Top up before it runs out. Check the level every few weeks. Your softener cannot regenerate without salt, and hard water will start to come through.
• Do not overfill. Keeping the tank about half to two-thirds full makes it less likely salt will bridge.
• Watch for a salt bridge. If the level never seems to drop, a hard crust may have formed with a gap underneath. Break it gently with a broom handle, taking care not to damage the tank.
• Clean it out now and then. If sludge builds up in the bottom of the tank, empty it and rinse it.

How much will you use?

That depends on how hard your water is, how many people live in your home and how efficient your softener is. A modern metered softener only regenerates when it needs to, so it uses less salt than an older timer model.

Not sure which salt your softener takes? Tell us the make and model on 0121 557 5532 and we will point you to the right one.