Water wise car wash with a Kärcher high-pressure cleaner and harvested rainwater

Washing your car in Cape Town is difficult due to the ongoing drought for well over a year now. But, I worked out how to use my Kärcher high-pressure clear in gravity feed mode with rainwater that I harvested. 🎉

Water Wise

The winter rainfall over the Western Cape has pushed the storage in our dams to 63.5% at the time of writing this post.

I started harvesting rainwater at our home as an experiment in 2017 with some success. We have 120L plastic refuse bins, positioned at each of the 4 down pipes from our roof. Using a cable tie, I fastened a piece of shade cloth at the ends of the down pipes to catch leaves and other debris. This has resulted in loads of clean rainwater to use.

Rainwater harvesting from the downpipe on our roof

I was desperate to make use of this water and finally use my Kärcher 2.21 high-pressure cleaner again. I found a video which showed the use of an alternative water source with a high-pressure cleaner by Kärcher UK.

I then contacted Kärcher South Africa about this and they pointed me to the Water Wise article on their website.

The setup

This was my first attempt at using an alternative water source and the gravity feed mode. And I am certain there is room for improvement.

Kärcher water filter

Preparing your water source

Whenever the 120L refuse bins are full, I add a few drops of Milton Sterilising Fluid to kill any germs. This is not necessary, but rather safe than sorry! 🤞

I have a 10L watering can which has a fine filter to catch any small particles the shade cloth missed. After filling the watering can with rainwater from the bin, I used a funnel to fill a 25L water container.

Connecting the water source

With our garden hoses all but useless due to the current ban on hosepipes, I cut off a piece about 2m in length. Then I filled the piece of hose with water and blocked both ends with my thumbs to reduce any air pockets. I plugged the end of hose with the connector into the high-pressure cleaner as you would normally do.

To protect the high-pressure pump, I purchased a water filter from the Kärcher Center in Milnerton. Their service is excellent!

Kärcher water filter

Removing the air lock

Switch on your high-pressure cleaner and run it without the lance at first. Once you have a steady flow of water coming out of the trigger gun, you can then attach the lance.

Having done this a few times, this process usually only takes a few seconds. Filling the hosepipe with as much water as possible reduces the time taken to remove the air lock.

Side note: I have not found it necessary to elevate my water source (as suggested by Kärcher).

Wash your car

If you have never used snow foam on your car, I highly recommend you try it! Not only does it do a great job of helping to remove dirt and grime, making it easier to wash later. But it also is loads of fun.

I use Kärcher’s foam jet connector with ultra foam cleaner to foam my car, after giving it a quick spray down at a low pressure.

Golf MK7 GTI snow foam

Allow the snow foam to dwell for about 5 minutes, but do not allow it to dry. You can then proceed to rinse off the foam with your high-pressure cleaner.

Wash your car with the two bucket method to prevent contamination of your clean water. Again, this is all done using harvested rainwater.

My current favourite car wash shampoo is Meguiar’s Gold Class.

Our water wise car wash at home

Reminder: keep an eye on the water level of the container so that the high-pressure cleaner does not run dry.

Conclusion 👌

I have been able to rinse, foam and rinse a car with less than 50L of harvested rainwater. Not only is using a high-pressure cleaner a lot more effective, but it uses less water.

Having washed our cars with buckets of water, I can confidently say it is less efficient. There is just so much water that runs off into the road, compared to the little used by the high-pressure cleaner.

One improvement I’d like to make would be to find a small trolley to put the 25L water container on. This would make moving it around a bit easier, as your other hand is generally holding the trigger gun.


Find out more about car detailing

Check out the likes of Ammo NYC, Car Cleaning Guru and Autogeek for great tips.

More from my journal →