7.1 Rinsing Your Vehicle With De-ionised Water

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7.1 Rinsing Your Vehicle With De-ionised Water
7.1 Rinsing Your Vehicle With De-ionised Water

Rinsing your vehicle after washing may seem an obvious step. There are however, products which will affect how easy it is to dry your car and help keep it free from water spot marks.

Water spots – those annoying, difficult to remove, potentially damaging irritations which seem to appear in places you thought you’d thoroughly dried off. Water spots are left when water evaporates leaving behind mineral deposits – so cars should never be washed and rinsed in direct sunlight where the heat will cause water to evaporate more quickly. In rainwater the most prevalent of evaporates is precipitated calcium carbonate – also known as PCC. From rinse water there are likely to be other impurities, primarily calcium and magnesium, but possibly also sodium, copper and iron.

De-ionised water filters offer a solution to water spot marks. These innovative filters contain an electrically charged resin which neutralises impurities in the water through ion exchange. De-ionising water filters usually state their purification capabilities in terms of parts per million (ppm), for example neutralising ions in the water to produce de-ionised water to 30ppm or 0ppm . If you have a black car it will show up water marks far more than a lighter coloured car so you may wish to opt for the highest level of filtration available (0ppm).

With the impurities in the water largely neutralised, it is usually possible to allow the car to air dry, rather than having to use a drying towel. This time and energy saving benefit is usually the deciding factor for those considering whether or not to purchase a de-ionising water filter!


  • De-ionising water filter with hosepipe connectors
  • Hosepipe connected to mains water


  • Ensure car is rinsed free of wash suds
  • Connect filter to hosepipe
  • Using a steady flow setting drench the bodywork, roof and windows thoroughly with deionised water
  • Allow vehicle to dry naturally, NOT in direct sunlight

Caring For Your Filter:

  • Remember the more water forced through the filter, the shorter the life span, so use it for a final rinse only
  • Do not use the filter in conjunction with a pressure washer
  • Do not use the filter in conjunction with a domestic water softening system (these have the effect of adding salts to the water so the filter has to work to remove these as well as the other impurities)
  • Connect the filter to the spray head the end of the hose, rather than at the tap end. Less de-ionised water will be left in the hosepipe when you’re finished rinsing, so there will be less waste
  • Always connect the filter the same way, so the water passes in the same direction through the resin each time
  • When finished rinsing, disconnect the filter and allow water to drain out of it. Leaving water in the resin will affect its longevity
  • Never leave the filter in direct sunlight – many resins are affected by solar radiation

Video Demonstration:

Browse De-ionising Water Filters

7.1 Rinsing Your Vehicle With De-ionised Water PDF

Category: 7. Final Rinse

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