A dishwasher requires that you add both detergent and rinse aid. You’re most likely aware of that if you have used a dishwasher on a regular basis and understand how they work.
You might be surprised to know that your dishwasher might also need salt. Yes, that’s right: Your dishwasher might have a salt dispenser that takes a specific type of salt and there is a very good reason for this.
Dishwashers work best with softened water that has been heated to between 130 and 170 degrees depending on the model. Many dishwashers include a built-in water softener to provide soft water and it requires salt to operate.
Using hard water in your dishwasher requires more detergent and can make it harder to clean dishes whereas softened water generally means less detergent used and less work to remove dried food. Hard water also tends to leave stains and marks on glasses.
Below, we’ll take a closer look at what type of salt you should add to your dishwasher, how often to add it and how to tell if you even need to do so. We’ll also discuss soft vs hard water and other aspects of dishwasher salt that you need to know about.
Why does a dishwasher need salt?
Modern residential dishwashers often include a built-in water softener just in case you don’t have a water softener in your home or in case you live in an area where salt-using water softeners are no longer allowed.
A dishwasher – and your washing machine for that matter – perform best with softened water. Soft water is water that has harsh minerals like calcium and magnesium removed through the use of a water softener.
Soft water is also easier on your skin and hair when washing with it and is also much gentler on your pipes and appliances.
Hard water on the other hand has a high(er) concentration of dissolved minerals and is harder on the skin and hair and your pipes and water-using appliances.
What benefits does a built-in water softener offer your dishwasher?
A whole house water softener can be expensive and may not even be allowed in your home area. Having one built into your dishwasher provides you with softened water just for your dishwasher which helps to prevent limescale built up and watermarks on your cups, cutlery and dishes. Soft water is also better for your pipes.
Softened water also helps your detergent perform better and typically means you can pour less detergent if you use crystals.
Water hardness is something that is very specific by region and can vary wildly depending on where you live. Naturally occurring minerals in the ground near your water supply can cause your local water supply to be very hard. If you own a water softener it softens the water to account for this.
Some jurisdictions don’t allow new installation of water softeners given that highly concentrated salt water is dumped into the sewers during the regeneration process that occurs regularly. In that case you might not even be allowed to buy a dishwasher in your area with a water softener built in.
Best to check your local laws to see as it can change over time. If you are in the market for a water softener, check out this additional article I wrote on the subject.
What kind of salt does my dishwasher need?
Dishwasher-specific salt is 99% pure or better. Table salt on the other hand is typically 97% – 99% pure and can contain sodium aluminosilicate, magnesium carbonate and other additives that while fine for cooking, is not desirable for your dishwasher.
Your dishwasher salt on the other hand may contain anticoagulants that help to ensure it doesn’t block your system.
You can purchase dishwasher salt that gets added directly to the salt dispenser. This dispenser is typically located on the floor of the dishwasher with a round plastic screw cap like in the photo above and below.
Your cap might even have the word “salt” written on it to make it even easier to find.
Do you not use regular table salt that you buy in the store for cooking purposes!
Dishwasher salt is made of larger, coarser granules so that it takes time to dissolve and won’t clog your system. Table salt and other types of salt may also contain additives such as anti-caking agents which a water softener system does not need and could damage the system.
Using dishwasher salt specifically ensures that there will be no residue left on your dishes which may not be the case with non-dishwasher specific salt.
Do yourself a favor and only buy dishwasher-safe salt to use in your dispenser.
How often do I need to add salt to my dishwasher?
Depending on how frequently you use your dishwasher, you can refill the salt dispenser about once per month unless your dishwasher has a salt refill light or indicator in which case you can just follow that.
The frequency of refilling your salt dispenser also depends on the hardness of your water to start with. A water softener uses as much or as little salt as is necessary to achieve soft water. The harder the water to start with, the more salt will be required.
You only have to fill the salt to the water level inside the salt compartment so once it’s full, it’s full.
What if my house has a water softener?
If your house has a whole house water softener and the supply is used by your dishwasher, as long as it is producing softened water, you won’t need to further add salt to the dishwasher.
Dishwashers with built-in water softeners are popular in Europe but you can also find them in the United States. So depending on how common whole house water softeners are in your area – assuming they are legal – you may or may not need a dishwasher with a built-in one.
So built-in dishwasher water softeners are particularly useful if you don’t want a whole house water softener or aren’t allowed to install one where you live.
If you already have a water softener operating in your home, you may also find that you can reduce not only detergent use but will use less rinse aid as well although given that it’s automatically dispensed, it’s often an all or nothing proposition that you can’t personally adjust. Some dishwashers do allow you to dial back on rinse aid manually, which could come in handy.