Is Water Softener Effective Against Water Spots?

If you choose to wash your car with hard water, it leaves behind water spots that are difficult to remove.

But does soft water prevent water spots and can you use water softener on hard water to avoid water spots on your car?

Water softener does not prevent water spots on cars. It only removes and replaces calcium and magnesium with potassium and sodium. Also, it does not remove the Total Dissolved Solids (TDS). TDS are the main cause of water spotting potential. Softening helps replace magnesium and calcium minerals with potassium or sodium and forms water spots that are easy to remove.

As such, softening water makes the car washer’s job easier.

The spotting formed when you wash the car with soft water can be removed by just washing and wiping off.

Continue reading to find out if water softening really helps to prevent car water spots.

Does Water Softener Prevent Water Spots On Cars?

Washing the car leaves some water on the surface. When the water evaporates, it leaves behind residues.

If left to dry up on their own, the minerals form spots that are difficult to remove.

Softening water thus replaces stubborn minerals like calcium and magnesium.

It replaces them with sodium and potassium, which forms water spots that are easier to remove. 

Softening removes minerals attributed to the hardness of the water. Therefore, washing the car with softened water will likely result in a spot-free wash. In addition, softened water produces soapy lather; thus, you use less soap but achieve better results. Also, the subsequent spots formed are easier to clean and remove.

You can achieve better results by washing the car with low TDS water.

Low TDS water is deionized and has fewer minerals. Such water does not leave behind residues and is the best for washing cars.

Deionizing removes most minerals and may result in a spot-free wash. Unfortunately, it is impractical to get deionized water for home use.

What is available is softened water.  Water softeners only reduce the number of minerals in water but do not eliminate them.

Thus the low calcium and sodium content in softened water will still leave marks that are easy to wipe away.

Notice that calcium and sodium do not affect presoaks and detergent. Therefore, you save on soap when you wash your car with soft water.

It foams quickly and allows you to obtain a clean rinse faster. It reduces the formation of water spots.

Does Water Softening Make It Easier To Wipe Off Resultant Water Spots?

Softened water does not prevent the formation of water spots on cars.

However, cleaning the car with softened water forms water spots that are easier to remove.

Also, soft water does not form the scales you see on the car after washing with hard water.

Softening water does not eliminate TDS; it only reduces them. So, you will still have some spots that you can remove by wiping. It removes calcium and potassium and makes wiping the resultant spots formed easier. Calcium and magnesium are hard minerals that leave colored spots on car surfaces after washing

Therefore, it is recommended that you use soft water because the hard minerals are replaced with potassium and sodium minerals. 

Typically, spotting occurs when the water evaporates, leaving behind the Total Dissolved Solids which eventually form the spotting.

Softening the water, thus,  reduces minerals and makes it easier to remove the subsequent spots formed by wiping the surface with a rug. 

Note that washing the car with water that has undergone Reverse Osmosis produces better results because such water is low in TDS.

It guarantees a spot-free rinse.

Is Soft Water Better For Washing A Car?

When you wash the car with hard water, it leaves behind water spots that are difficult to remove.

Moreover, hard water makes it difficult for the detergent to dissolve and foam.

Besides, the chemicals in detergent react with the minerals in hard water to corrode surfaces.

Generally, low TDS water is the best for washing the car but it is too expensive for domestic use. So using soft water could be the only option you have. Soft water forms spots that are easy to wipe off using a microfiber towel.

Softening water reduces the surface tension and makes water molecules drift apart.

It further reduces water spots and the few that are formed are easy to remove since they lack calcium and magnesium.

Softeners play a critical role in car washing; they replace calcium and magnesium found in water with sodium.

Therefore, the spots formed when the car is washed can be removed by wiping.

Also, sodium ions do not affect detergents; thus, soft water is the best to use alongside presoaks and detergents.

Washing your car with soft water achieves better results than washing it with hard water.

However, you may need to follow some procedures to get better results. For instance, you must wipe out the spots formed using a microfiber towel immediately.

It ensures no water is left to dry and form hard spots. 

But when you wash with hard water, you may not get the same resuylts even if you wipe it with a microfilm towel. 

Hard water forms spots that are difficult to remove and may require you to use advanced techniques to remove them. 

Note that soft water has low salt content, so it easily removes scaling when washing a car. Besides, it makes detergents to foam faster. In fact, any water spots formed can be removed by wiping off the surface.

Also, soft water works well with detergents and presoaks. Thus, using it reduces the amount of soap you use to clean your car.


  • Using softened water does not eliminate hard spots but reduces them.
  • Water spots formed when you wash your car with softened water are easy to remove
  •  Rinsing the car with distilled water or water reduces water spots.
  • The higher the TDS level, the more spotting you will experience after washing your car.


Jan-Lucas Ganssauge
Jan-Lucas Ganssauge