Side-by-side shot of a water softener at left and a dishwasher at right

A dishwasher is an essential appliance for cleaning dishes in modern kitchens.

However, the quality of the water that enters the dishwasher affects its efficiency and longevity.

Hard water is a common issue since it contains minerals like calcium and magnesium that should be removed before the water enters the dishwasher. 

Therefore, should a dishwasher be connected to a water softener to solve the hard water debacle?

This article will discuss how a water softener helps prevent limescale that affects a dishwasher.

We’ll also cover how to set up your dishwasher for softened water and suitable alternatives to installing a water softener. Let’s begin!

Should a Dishwasher Be Connected to a Water Softener?

The dishwater should be connected to a water softener to enhance its efficiency and lifespan.

Calcium and magnesium minerals in hard water lead to a buildup of mineral deposits in the washer. These deposits reduce water pressure and detergent efficiency, lowering the dishwasher’s efficiency.

How Does a Water Softener Prevent Limescale?

Hard water is widespread in most parts of the world.

In fact, 90% of American homes use hard water.

Although hard water is not dangerous for human health, it can wreak havoc on household appliances like the dishwasher by forming limescale.

A water softener comes in to help safeguard your appliances by preventing the formation of limescale from the hard water. However, you may wonder how the softener achieves this.

Water is classified into two categories based on mineral composition:

  • Hard water contains a high amount of minerals like magnesium and calcium, calculated in grain per gallon (GPG) of calcium carbonate. Hard water acquires these minerals as it percolates through limestone, gypsum, or chalk.
  • Soft water contains lower levels of calcium and magnesium minerals in GPG.

The minerals present in hard water are responsible for limescale formation. A water softener removes these minerals from the hard water (zero GPG), converting it into soft water. Thus, it prevents the accumulation of limescale in the dishwasher.

The top of an open water softener being filled with salt by a homeowner

Connecting your dishwater to a softener protects it from hard water, guaranteeing maximum efficiency and a longer lifespan.

The following is a water hardness scale to help you know when the water is unsafe for your dishwasher:

Grains Per GallonMg/L and PPMClassification
Less than 1Less than 17.1Soft
1 to 3.517.1 to 60Slightly hard
3.5 to 760 to 120Moderately hard
7 to 10120 to 180Hard
Over 10Over 180Very hard

Table 1: Water hardness scale

How to Set Up Your Dishwasher for Softened Water

What next after connecting your dishwater to a water softener? You need to set it up to use softened water. Luckily, it’s a simple process—all you need to do is set the dishwasher’s water hardness to zero.

Your dishwasher’s manual has instructions on how to set its water hardness to zero.

If you’ve lost the manual, you can search the procedure online for your dishwasher brand and model.

Also, you should reset the electronic water softener regeneration cycle to ensure it’s producing soft water. After doing so, your dishwasher is set up for softened water use.

Here is a demonstration video:

How to Set the Water Softening System on Your Thermador Dishwasher

If you’re interested in learning if a dishwasher or hand washing is more sustainable, check out this article to find out. 

Alternatives to Installing a Water Softener

If your current financial situation prevents you from installing a water softener, does it mean you’ll be stuck with hard water? The answer is no.

You can still deal with hard water in the following ways:

  • Use a high-phosphate detergent – phosphate is an excellent water softener. Modern detergent manufacturers include phosphate in their detergents to prevent the formation of limescale. Therefore, if you don’t have a water softener, check your detergent labeling for the presence of phosphate.
  • Use limescale prevention products – you can also choose to use specially designed limescale prevention products in your dishwater. These products are available as additives and tablets for different dishwashers.
Various dishwasher tablets stacked on each other
  • Use a descaler – as opposed to a water softener, a descaler doesn’t reduce the water’s GPG; instead, it prevents the secondary effects of hard water, like limescale deposit on your dishwater.
  • Using salt (for recommended dishwashers) – some dishwashers have a container on the inside bottom where you can add salt. This addition helps soften the water, although it’s less efficient than a descaler or detergent with phosphate.

It’s also advisable to turn on the rinse aid in your dishwasher – this mode reduces the dishwasher’s water surface tension, enabling it to flush away dirt and limescale from its interior efficiently.

Effects of Hard Water on Dishwashers

Hard water affects your dishwasher and its washing efficiency in the following ways:

Reduced Water Pressure

A dishwasher needs sufficient water pressure (20-120 pounds per square inch) to fill up quickly and clean the dishes effectively.

Moreover, this pressure ensures that the water level remains below the heating components to prevent damaging the dishwasher.

Hard water significantly reduces a dishwasher’s water pressure due to the formation of limescale deposits in the inlet valve.

Spots or Film on Dishes

When the water pressure is low, the water doesn’t fill up the dishwasher to the required level. Consequently, the dishes on the top rack don’t get sufficient water; thus, they remain dirty.

Even when you add detergent or use the rinse aid, the dishes may still have spots and films due to the deposits of minerals from hard water.

A homeowner admiring a spot-free glass as she pulls it out of the dishwasher

It’s also worth noting that hard water impedes the dishwasher heating element from reaching its required temperature for efficient washing. Consequently, your dishes might not get fully clean.

Accelerated Wear and Tear

When limescale forms on your dishwasher’s interior, you’ll have to remove it using a descaler or vinegar.

Unfortunately, the removal process involves scrubbing or running a cleaning cycle, accelerating your dishwasher’s wear and tear.

Moreover, if you don’t remove the limescale, it accumulates, reducing the dishwasher’s water pressure. 

Finally, hard water reduces your dishwasher’s lifespan by corroding the metal components like the sump pump and heating elements over time.


A rusting dishwasher is the worst effect of hard water.

Some of the minerals in hard water are salty. As you know, salt is catastrophic for metal components.

When the salt comes into contact with the dishwasher’s metal components, it causes rusting.

Therefore, if your dishwasher has been exposed to hard water for an extended period and you can see signs of rusting, it’s time to replace it.

The Pros and Cons of Connecting a Dishwasher to a Water Softener

As with anything else, connecting your dishwasher to a water softener has both its pros and cons. You need to be aware of both to make an informed decision.

The table below shows the pros and cons of connecting a dishwasher to a water softener.

Reduced mineral depositsHigh sodium content on the dishes
Longer appliance lifespanNot necessary for all dishwashers
Energy efficiencyHigh sodium content in wastewater
Soap and detergent savingInstallation and maintenance costs
Minimizes scale buildupHigh operating costs
Table 2: Pros and cons of connecting a dishwasher to a water softener


Should a dishwasher be connected to a water softener? Yes, securing your dishwasher with a water softener enhances its efficiency.

Hard water significantly reduces the machine’s efficiency by lowering its water pressure, spotting or filming dishes, accelerating wear and tear, and rusting its metal components.

If you can’t afford a water softener, using a phosphate-based detergent or salt (only for approved dishwashers) can help soften the water.

Now that you know why you should connect your dishwasher to a water softener, check out this article to know if dishwasher pods are bad for the environment.

Leave a Reply

Your email address will not be published. Required fields are marked *