What Does Dishwasher Salt Do

If you live in an area where your water supply supplies you with what is known as hard water, you might notice an annoying white residue on your dishes or cloudy glassware.

This is indicative of a poor wash that is caused by the hard water itself. If you aren’t careful, it could mean that your dishwasher is being put through the wringer and suffering unnecessary damage from the hard water. If the hardness of the water is above 9°E, the water needs to be softened.

Using salt in your dishwasher may sound outlandish and strange, but it can be a reliable method of softening the water to better clean and prevent residue. If you’re a bit skeptical, here is how it works.

What is Dishwasher Salt?

Before we explain how this process works, let’s first briefly explain just what it is. This type of salt is unlike common varieties, such as table salt, sea salt, and Kosher salt. A more significant difference you’ll note is the size. The consistency and size of those more commonplace salts are far finer and smaller, which is why the salt can cause blockage in the drainage of your dishwasher. Dishwasher salt is much chunkier and looser so it avoids disturbing the cleaning of dishes.

The chemical structure is also an important distinction. Dishwasher salt has the same makeup as other salts – sodium chloride – but it is typically 100% pure, with no additives.

This is opposed to your average table salt, which often contains compounds such as magnesium. Pure sodium chloride is practically 100% safe to be in your dishwasher, but the additives of table salt can cause damage to the mechanical components as well as help in the creation of hard water stains.

The Purpose of Dishwasher Salt

If you live off a supply of soft water, you may not be acquainted with the concept of hard water and what it does to your dishes. Hard water has a higher mineral content, often rich in magnesium and calcium, and less commonly, lime, gypsum, and chalk. These minerals are responsible for the residue you find on your dishes and inside the dishwasher after you’ve used it.

There is a common misconception as to what dishwasher salt does for you. In areas rich in hard water, such as various countries in Europe, dishwasher salt is used to regenerate the resin in the ion exchange systems. Dishwashers built to handle hard water contain a built-in water softener that removes calcium and magnesium ions in the water. This lowers the overall concentration of calcium and magnesium that gets into the washing cycle.

How Does it Work?

Inside the filter we mentioned earlier, you will find a filter of sorts consisting of a basket and small resin balls. When hard water containing magnesium and calcium passes through this filter of resin balls, the resin balls absorb the particles and soften the water, creating much cleaner, dishwasher-safe water.

Over time, the resin balls will become negatively charged and will thus require resetting. This is where the dishwasher salt comes in. The negatively charged resin balls attract the sodium ions in the positively charged salt, resetting the resin balls to be an effective filter and softener once again. This entire process is well-known as ion exchange.

White granulated Dishwasher salt to soften water, Salt in wooden spoon

How Do You Use Dishwasher Salt?

You should never use dishwasher salt in a dishwasher that does not have a dedicated compartment for it. A dishwasher with a water-softening system built into the components will more than likely have a salt compartment. You’ll likely find it somewhere around the bottom basket. To use it, all you need to do is fill the compartment up with the salt, up to the specified capacity for the particular model of dishwasher you have, close it, latch, and then you’ll be ready to go.

If there is still water in the reservoir, you should still be able to add some dishwasher salt safely. But be sure you always check the manual for your particular model for specific directions. How much you add also depends on the hardness of the water. The packaging of your dishwasher salt should tell you how much to use.

The salt indicator is an excellent way of measuring how much salt is required. However, not all machines have one of these built-in, making it more difficult to gauge how much is needed. As a general rule of thumb, if you’re unsure, simply fill it up.

It’s crucial you don’t put the salt anywhere where you would put your normal detergents. This can cause a lot of damage to various components, including your dishes. The salt never actually gets close to your dishes and only affects the water going in. Putting it into a different part of the rinse cycle can cause it to leave your dishes dirty and with salt build-up.

Do You Need Dishwasher Salt in a Soft Water Area?

The whole point of dishwasher salt is to reset the water-softener in your dishwasher. Naturally, if you already have soft water coming from your water supplier, it would render the point moot and a waste of money. If you are unsure of the hardness of your water, contact your water supplier to find out if softening the water is necessary.

Remember that hardness of around 9°E is considered too much for most machines. You will require a water softener. If your washing machine does not have a built-in softener, then you might want to consider investing in a filtration system. However, this can get quite pricey. So you might want to consider investing in a washing machine that instead has a softener built-in.


If you live in an area with hard water, having a dishwasher that can soften water is essential. If your dishwasher doesn’t have the capacity for it, seriously consider investing in one. It will help remove any residue you may be suffering from. Additionally, it will keep your dishes and glassware cleaner than ever before, eliminating all squeaks, streaks, and build-up.

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