Why Do Dishwashers Need Salt? [How Much + How Often It’s Needed?]

Image of salt in a dishwasher

We all add salt regularly to our dishwashers, and when the salt levels fall, the machine blinks an alarm signal. So why do dishwashers need salt?

Dishwashers need salt to decrease the water hardness, which means removing calcium and magnesium salts from the water. This process is needed because it allows the washing detergent to clean up dinnerware and pots efficiently. It also helps eliminate scale buildup, which can damage the dishwasher.

There are other reasons too that we have covered in more detail below. We’ll also explain exactly how much salt is needed and when is the right time to replenish dishwasher salt.

How Dishwasher Salt Differs From Regular Salt?

Dishwasher salt is quite similar to regular salt. They both have the same basic chemical composition: a sodium chloride molecule.

However, dishwasher salt is an industrial material designed and manufactured to fulfill a specific function.

The main differences between dishwasher salt and table salt are the following:

  • The grain size of dishwasher salt is generally much larger than sea salt. This makes them easily distinguishable.
  • Dishwasher salt is made in a much purer form than table salt. The latter usually contains added iodine plus some other impurities. If these particles find their way into a dishwasher, they’ll most probably cause serious damage.
  • Many manufacturers add color to dishwasher salt to deter anyone from using it in seasoning food. Despite its pure form, this salt isn’t a food-grade product, and it might contain other chemicals. So you should never use it for cooking.
  • Dishwasher salt takes much longer to dissolve compared to regular salt. This is taken into consideration while making dishwashers. So swapping this type of salt with a quick-dissolving variety wouldn’t work at all.

5 Reasons Why Dishwashers Need Salt

Dishwasher salt is essential for the proper functioning of a dishwasher to the point that an alarm blinks and the machine stops working when its levels are too low.

Dishwashers need salt for the following reasons.

1. Reinvigorate the resin in the water softener.

The main reason why dishwaters need salt is to reactivate the resin bed inside its internal water softener.

Back in the day, water softeners were complicated structures that needed to be installed in external water treatment units.

They converted hard water into soft water. Then, that better quality water got fed into various sensitive machines.

Some appliances that constantly used water stipulated the use of external softeners to ensure that the water used had specific properties.

Otherwise, the outcomes weren’t optimal. This included industrial washing machines, boilers, and sterilizers.

In recent years, many devices opted to include an internal water softener. This way, the water fed into the machine would always be of the best quality.

A resin material is an integral part of any ionic exchange water softener. This is where the calcium and magnesium salts from the hard water are extracted and pulled out to decrease the water’s hardness.

This material gets clogged and ineffective after a while. And to keep it active, the resin needs a regular dose of sodium chloride or salt.

A dishwasher has that built-in softener, and that’s why we need to replenish its salt regularly.

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2. Allow the soap to develop a lather.

Dishes being washed in a dishwasher

Most of us have sometimes tried to use soap with tap water, but the soap seems to stop working altogether.

Using more water actually makes matters worse, and the soap just ceases to produce any lather at all.

This is a typical situation whenever the water’s hardness exceeds the normal levels.

The calcium and magnesium salts inherent in the water react with the soap to create a sloppy insulating layer all around the soap. This renders the soap completely unusable.

A similar situation happens with dishwashing detergent. Hard water weakens, even neutralizes, the detergent’s ability to clean anything.

That’s why salt is needed in a dishwasher to decrease that hardness and let the detergent do its job effectively.

3. Get perfectly clean glassware and dinnerware.

Softwater is a must to operate a dishwasher effectively. Otherwise, stains and smears appear on glassware.

If hard water isn’t treated with a softener before using it in the machine, then this unsightly result is inevitable.

Furthermore, using a softener with clogged resin fails to remove the water hardness. It’s then essential to reactivate it with salt and get it back in good form.

Using more powerful detergents, ramping up the washing temperature, or selecting a longer program, doesn’t really solve the problem.

That’s because it’s caused by the poor water quality. And once the salt is replenished, glassware comes out of the dishwasher, all clean and shiny.

4. Minimize scale buildup.

The calcium and magnesium salts in hard water are notorious for creating a layer of white solid residue on surrounding surfaces.

This happens in swimming pools, faucets, filters, pipes, and especially kettle heating elements.

All these things need regular descaling to keep functioning in a satisfactory manner.

Sometimes, a water softener is added to the water inlet before it’s fed into a facility. This usually minimizes scale buildup.

Part of the process is adding salt to the system for keeping the softener active.

This is another good reason why salt is needed in a dishwasher.

5. Avoid machine deterioration.

Scale buildup in any machine isn’t just a bad look. It could cause functional damages over time. Corrosion, blockage, and compromised heating are among the common issues caused by scale buildup.

Once this happens, the machine starts showing error messages or even stops working altogether. A visit from a maintenance specialist is needed to fix this, which comes with extra costs and downtime.

If the main issue isn’t solved, these service visits become frequent. Sometimes malfunctioning parts of the machine would need to be replaced. More importantly, the longevity of the machine is significantly reduced.

Additionally, these scales provide a nice home for various types of dirt, bacteria, fungi, and other unsavory pollutants. This defies the whole point of using a machine for washing dinnerware and other utensils.

Adding salt helps in optimizing the water softening process. This takes out calcium and magnesium from the water, thus, minimizing the scale buildup inside the dishwasher.

How Much Dishwasher Salt Should You Add?

Most people buy dishwasher salt in bulk. This usually raises the question of how much salt is needed for the machine to work efficiently.

Luckily, most dishwashers remove the guesswork from this step. The salt container often has a mark that should be reached and not exceeded. So users simply need to keep filling until the salt touches that marked line.

When the salt gets used up, you don’t need to do an inspection. Instead, the machine panel typically gives a “Low salt” signal. Some dishwashers stop working until this issue is fixed.

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How Often Should You Add Dishwasher Salt?

Typically, you should replenish dishwasher salt every 1 to 3 months. This depends on:

  1. The model and size of the dishwasher,
  2. Dishwasher usage, and
  3. Water quality.

A larger machine would use more salt than a smaller countertop one. This is because it uses more water and has a bigger volume. Naturally, this speeds up salt consumption.

Big households with lots of kids produce plenty of soiled pans, dishes, and glasses.

These families need to operate their dishwashers more frequently than a newlywed couple would. This translates to a clear difference in salt consumption.

Water quality is also a big determinant of how much salt is used up. If the incoming water is already soft, then the water softener doesn’t have much work, and the salt remains intact.

On the contrary, softening really hard water uses up plenty of salt.