Water Quality and How it Affects the Car Wash!

Water quality in Ireland can be quite varied from county to county with Cork being a lot softer than Dublin and Galway. This water quality affects the car wash in several ways. They include, equipment wear, chemical performance and end result final finish.

Water Hardness

Hardness is a term that refers to the content of certain minerals in the water. These are primarily calcium and magnesium. Virtually all water contains some degree of hardness. This varies though depending on the type of rock the water filters through. Hardness is measured in Europe as parts per million and in the U.S as grains per gallon. As a guide 17.1 parts per million (ppm) is equal to 1 grain per gallon (gpg) Soft water is defined as having less than 17.1 ppm. The following table gives an indication of soft and hard water.


Grains per Gallon

Parts per Million


Less than 1.0

Less than 17.1


1 – 3.5

17.1 - 60

Slightly Hard

3.5 – 7.0

60 - 120

Moderately Hard

7.0 – 10.5

120 - 180


10.5 and Higher

190 and Higher

Very Hard


From tests we have previously conducted. As a guide we found the following counties had these hardness levels:

Cork - 102 ppm, Carlow - 185 ppm, Dublin – 200 ppm, Galway – 210 ppm, Limerick – 220 ppm

This shows that in Ireland, almost all counties are classed between moderately hard or Very Hard.

 Equipment wear

Hard water is typically high in mineral deposits, these deposits build up in pipe-work which cause blockages and typically corrode heater elements in jet washes and touch-less washes. This Calcium fallout is a result of calcium dropping out of solution as it reacts with the car wash chemicals. This build up also blocks valves and results in erratic pressure which lowers customer satisfaction!


Chemical performance

The Calcium and Magnesium found in water are very soluble and look for ingredients to attach themselves to. These other ingredients are found in the car wash chemical! When a reaction takes place the active ingredients in the car wash are neutralized! As hardness increases, more chemical concentrate is needed to achieve cleaning. In contrast, by using soft water, the wash operator needs less chemical. The following table shows the savings when softened.


Original hardness

Approximate savings when softened

35ppm - 85 ppm


85 ppm – 170 ppm


170 ppm – 235 ppm


235 ppm – 300ppm


300ppm +


 Chemical savings and increased performance can be achieved when softening the chemical water!

End Result

Another problem caused my hard water is spotting on the vehicles surface after the wash has finished. This is caused when the water on the vehicle evaporates and leaves behind the mineral deposits that were in the water. Any water higher than 20ppm will cause spotting! The way to remove this problem is by adding a Reverse osmosis system. This system filters out 99.9% of minerals in the water. This system consists of a R.O filter, a storage tank and a pump. The R.O system produces the water, it is stored in a storage tank then used as a final rinse after the washing process has finished (before the dryer). As the mineral deposits have been removed, any water that is left on the vehicle will evaporate and leave no traces of deposits. Giving a “Spot Free Finish” and a shiny car!


Happy car washing!