When you are at the grocery store you might have noticed that there are some boxes next to the dishwasher detergent containing salt. This is salt is essential for the performance and lifetime of your machine, here is why you need to put salt in the dishwasher.

Dishwashers have an internal water softener to remove calcium and magnesium from the water, making it soft. The water softener uses salt (NaCl) as the active chemical to regenerate the softener between dishes.

Soft water makes the detergent more effectively and will help with reducing limescale and streaks on your dishes. A risk of not using soft water is blocked washer jets and deposit on the heating element and inside the machine from limescale, shorten the life of the machine.

Where do you put salt in the dishwasher?

The salt reservoir is located on the bottom of your dishwasher. After removing the lower tray unscrew the big lid covering the reservoir. Most manufacturers will include a funnel to make it easier.

What type of salt do you put in the dishwasher?

Always use salt that’s meant for use in dishwashers, like Finish Dishwasher Salt from Amazon. Even if the salts chemical formula is the same chemical formula we normally call table salt, sodium chloride (NaCl). Dishwasher salt is designed to dissolves gradually and not to block the softener unit, that’s why it has a coarse structure. Normal table salt might have anticoagulants that cloud lead to clogging of dishwasher or addition of magnesium salts, the chemical the softener tries to remove.

How often do you put salt in the dishwasher?

There is no recommendation that fits all and it will come down to the hardness of your water. Most manufacturers like Bosch has a salt indicator light to indicate when it needs a refill. A good recommendation is to check the salt level every month and just top it up. Remember that salt has a very important job and will impact the lifetime of your dishwasher if you stop using it.

What is hard water?

Water hardness is referred to the amount of dissolved calcium and magnesium in the water. If you have hard water you might notice it from a film on your drinking glasses or the reduced efficiency of soap. This can be felt when washing your hands and they still feel slimy when you are done. The easiest way is to contact your local water plant and get the amount of calcium carbonate in your drinking water.

General guidelines for classification of waters are: 0 to 60 mg/L (milligrams per liter) as calcium carbonate is classified as soft; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as hard; and more than 180 mg/L as very hard. (USGS)

Reference

The quality of our Nation’s waters: Water quality in principal aquifers of the United States, 1991-2010 Circular 1360 By: Leslie A. DeSimone, Peter B. McMahon, and Michael R. Rosen
https://pubs.er.usgs.gov/publication/cir1360