Why You Need Dishwasher Salt (and What Is It Anyway?)

Most people who have hard water in their homes know it because of stains and soap scum that accumulates on faucets and shower fixtures. But hard water stains (which are really hard to remove) can also show up in the dishwasher. If you’ve ever noticed cloudy glasses or a chalky residue on your dishes after running a cycle, it indicates that your dishwasher is suffering from hard water, too. The secret to getting your dishes—and dishwasher—sparkling clean could be as simple as adding a product you may or may not have heard of yet. We asked an appliance expert to share what dishwasher salt is and who should be using it.

What Is Dishwasher Salt, and How Does It Work?

“Dishwasher salt is a grade of granulated sodium chloride used to soften hard water and prevent limescale buildup in dishwashers,” according to Mark McCann, director of product marketing, dish care at BSH. It’s specifically designed for use in the dishwasher and shouldn’t be substituted with table or sea salt. Although sea salt mainly consists of sodium chloride, it also contains other minerals and trace seawater elements. McCann emphasizes that using different types of salt—especially those that contain fine granules—can damage a dishwasher’s built-in water softening unit.

The primary purpose of dishwasher salt is to regenerate the water softener found in most dishwashers. Many appliance brands make dishwashers with a water softener that requires some maintenance, and that’s where dishwasher salt comes into play. “Its coarse, large granules help remove calcium and magnesium ions from water, which commonly appear as water spots or a hazy, leftover film on glassware following a dishwasher cycle,” explains McCann. Flushing out the trapped minerals not only helps to prevent buildup, it also ensures that your dishwasher continues to clean effectively.

Note that dishwasher salt doesn’t clean your dishes (at least, not directly), nor does it mix with dish detergent. Instead, it plays a behind-the-scenes role in making sure your dishwasher operates at peak efficiency. When you add dishwasher salt to the designated compartment, it dissolves in water and flows through the ion exchange system. This is the process that removes calcium and magnesium ions and replaces them with sodium ions, which wards off limescale buildup. As a result, your dishwasher can rinse dishes (and everything else!) better, leaving them spotless.

Should You Be Using Dishwasher Salt?

Whether you need to use dishwasher salt depends on your water’s hardness level and your dishwasher model. Per McCann, “If you have a dishwasher with a water softener, and you reside in an area with hard water, it is recommended to regularly refill the dishwasher salt compartment and utilize the water softener feature.” If you’re unsure of your home’s water status, he advises you to test it before deciding to use dishwasher salt.

You can use an at-home testing kit or check with your municipality’s water supplier. There will also be visible signs that indicate you have hard water. When it comes to your dishwasher and dishes, some of these signs include:

• Dishes that have residue, whether it’s chalky or as if the detergent didn’t dissolve completely
• Glassware that is cloudy or spotted
• White or chalky buildup inside the dishwasher

Next, refer to the manual to confirm your dishwasher model has a built-in water softener. According to McCann, “Bosch dishwashers are equipped with a water softener and have a sensor that will notify users when it’s time to add dishwasher salt.”If your appliance does not indicate when it’s time for a refill, consider how often you use it and the hardness of the water in your area as a guideline. If you have very hard water and use the appliance frequently, you should add dishwasher salt approximately once a month. However, if your water is softer and you use the appliance less often, you can reduce this to every few months.

McCann also points out, “If a user utilizes an in-home water softening system, the built-in water softener in a dishwasher may not be necessary.”

How to Use Dishwasher Salt

Adding dishwasher salt is a simple process, but it’s important to do it correctly to avoid unnecessary damage to your dishwasher. Here’s how:

1. Locate the dishwasher salt compartment. Most dishwashers feature a specific salt reservoir located at the bottom interior, near the drain.
2. Pour in the dishwasher salt. Unscrew the cap and—if it’s easier—use a funnel to fill the compartment with dishwasher salt. Note that there may be water in the reservoir, which is common. Screw the cap back on tightly so no salt leaks out.
3. Run a rinse cycle. Doing so will help evenly distribute the salt and remove any excess grains that may have spilled.