Does Homemade Laundry Detergent Work With Hard Water?

A blue cup on its side with laundry detergent spilling out onto a purple rug.

All water is not the same. If you have hard water, you know that it presents certain challenges.

For those that would like to avoid the chemicals found in many commercial laundry detergents, the answer would appear to be to make a homemade laundry soap with more natural ingredients, but will hard water pose a problem?

Does homemade laundry detergent work with hard water? By itself, homemade detergent is not very effective with hard water because the soap molecules react with the water’s minerals to form soap scum and deposits. However, adding water softeners, like vinegar, borax, or citric acid will allow the detergent to do its job.

No one likes dingy clothes or wasting time and hard-earned money making products that just don’t work, right?

Let’s look at which additives will give your homemade laundry detergent the boost it needs to work with hard water.

Can I Use Homemade Laundry Detergent With Hard Water?

The short answer is yes, it’s possible to make a homemade laundry detergent that will clean fabrics effectively when used with hard water. (I discuss the merits of both powder and liquid versions here.)

You just need to make some modifications.

Hard water is a common concern. In fact, some estimates put the percentage of hard water areas in the United States as high as 85%.

In the United Kingdom, an estimated 60% of homes have to deal with hard water.

Sadly, many people who struggle with hard water issues have tried homemade laundry products only to be disappointed by their performance. 

The problem wasn’t that their laundry detergent was faulty in any way. The issue was caused by the hardness of the water.

What Is Hard Water?

Water is classified as hard if it contains a high concentration of minerals, particularly calcium and magnesium.

The rates to determine whether or not water is hard differ from country to country. 

For example, in the U.S. water with more than 60 milligrams/liter of calcium carbonate is considered hard, but in the U.K. anything over 50 milligrams/liter is deemed hard. 

Calcium and magnesium don’t sound that bad, right? In fact, many people take calcium and magnesium supplements daily. 

While these minerals are indeed necessary for good health, they can wreak havoc on certain appliances and household plumbing, make cleaning your home and body a difficult chore, and cause laundry day to be more frustrating than it has to be.

Signs of Hard Water

If you’ve never had your water tested but suspect you may be dealing with hard water, take a moment to look around your home for the following common signs of hard water.

  • Film left on glasses and dishes.
  • Hands feel as if they have a residue after washing with soap.
  • Soap and shampoo don’t lather well when used.
  • Soap scum frequently appears in your bathtub, shower, and sinks.
  • White residue is often apparent on shower heads, faucets, tea kettles, and coffee makers.
  • Frequently clogged plumbing or decreased water pressure.
  • Electric water heater is not efficient or has a short life span.
  • Overall poor performance over time of any appliance that uses water.
  • Clothing feels stiff and gets dingier the more it’s washed.
  • White fabric becomes gray or yellow.
  • Mineral buildup or scum coats the inner tub of washing machine.

How Does Hard Water Affect Laundry?

Homemade detergent is a great way to save money and avoid potentially harmful chemicals.

(I go into more detail about the frightening ingredients of commercial detergents here.)

With most recipes, however, one of the main ingredients is usually soap, and therein lies the problem.

When soap comes in contact with hard water, it reacts with the minerals to soften the water. Great, right? Well, not really.

So much of the soap goes toward softening the water, that not much is left for actually cleaning your laundry. 

Another side effect of this softening is that new compounds are formed in the process that cling to fabric (and surfaces), attract and hold grime, don’t wash away easily, and accumulate over time. 

Those pesky mineral deposits can actually weaken the fibers of fabrics over time, leading to tears, holes, and a general grungy look.

So, your laundry isn’t effectively cleaned and might even come out dirtier than before! Is all hope lost? No way. There’s almost always a way around any problem.

How to Fix the Problem of Hard Water Ruining Laundry

While you can invest in a whole-house water softening system to treat all incoming water to your home or purchase either an electronic water softener or a mineral magnet to attach to an intake water line, if laundry is your main concern, there are several steps you can take to resolve just this issue. 

Of course, the most obvious step would be to add a water softener such as Calgon (I prefer the more natural Charlie’s Soap Booster) to each load.

This will indeed help, though it can get pretty expensive over time. Luckily, there are alternative solutions to explore.

Some people may note an immediate improvement in their detergent’s effectiveness by using just one of the following alternative solutions. 

Others may need to experiment with several combinations before finding the ideal pairing that works with their water.

Solution: Vinegar

Adding approximately ½ a cup of vinegar, either white (distilled) vinegar or apple cider vinegar (ACV), to the final rinse cycle of each load of laundry will help prevent residues from clinging to your laundry.

Whites will stay whiter, and colors will keep their brightness.

Why It Works

The potassium and sodium in vinegar dissolve calcium so that it will be harmlessly rinsed away.

Vinegar will also remove existing residues and buildup from laundry and hard surfaces, like the inside of your washing machine, so not only will your laundry get cleaner but so will your machine.  

Solution: Salt

To start, try sprinkling 1/2 of a cup of salt directly over your laundry before beginning the wash cycle.

If you don’t notice an immediate improvement, increase the amount until you see results. 

Why It Works

Salt, a natural water softener, contains sodium, which reacts with the troublesome magnesium and calcium ions, suspending them in the water so that they can be washed away.

Salt is also great for removing stains, keeping colors bright, dealing with yellowing or graying of whites, and is said to help fix colors to prevent bleeding in the wash.

Solution: Borax

Your homemade detergent likely contains borax already. If this is the case, double the amount you would typically use.

If your recipe doesn’t call for it, add ½ a cup or so to each load.

Why It Works

Borax effectively boosts the efficiency of your detergent, fights stains, disinfects, and deodorizes, but it’s also a terrific water conditioner and removes mineral deposits. Need proof? Check out the back of 20 Mule Team Borax

Borax is made up of boron, oxygen, and sodium.

In a wash cycle, the boron reacts with water to create hydrogen peroxide, a powerful cleaning agent. The sodium works to soften the water.

Solution: Citric Acid

Simply add ¼ – ½ of a cup of citric acid when making your basic homemade detergent.

Alternatively, you could add 1 tablespoon (more if your water is very hard) directly to each load of laundry.

Why It Works

Citric acid binds the magnesium and calcium ions to prevent them from clinging to your laundry. The compounds are then easily rinsed away and your clothes will be residue free. 

Solution: Washing Soda

Washing soda is another easy way to soften water.

Although your recipe probably already contains washing soda, for hard water, you’ll want to double the amount for each batch or just add an extra ½ a cup to every load.

Why It Works

Washing soda is sodium carbonate. By now, you know what the sodium does, but what about the carbonate?

The carbonate ions react with the calcium present in the water to form suspended particles of calcium carbonate, which can be rinsed away easily.

Solution: Oxiclean

Many people with mild to moderate hard water find that a scoop of Oxiclean in addition to your homemade product does a great job of softening the water sufficiently to get the laundry truly clean.

Why It Works

Like borax, Oxiclean forms hydrogen peroxide and contains sodium to soften water and remove tough stains.