how to make pure water for window cleaning

To make pure water for window cleaning, you need to pump hard water through a reverse osmosis system. Then test the water to make sure the tds reading is below 0.07. 

The purity of the water window cleaners use is very important, and if not done correctly there will be spotting left on the windows. In this guide we will show you how to make pure water for your window cleaning business.

The first thing you should do before buying a reverse osmosis is to check how hard your water is where you live. You do this by using a TDS meter that you can get from eBay here. Once tested, if your water is under 100 ppm then you will be able to use just a Di vessel if you wish.

In the long run it maybe cheaper for you to buy a RO system. The first thing you need to decide is a location for your reverse osmosis system. Some window cleaners have it in the back of their van and others have it in the shed.

Filtering the water in your shed


  • Water can be made in advance
  • You can use the van while the water is being made
  • Less chance of freezing


  • The storage tank takes up a lot of room
  • You may need a submersible pump
  • You need somewhere to drain waste water

Filtering water in your van


  • You can filter water in whatever location you are in
  • No need to pump water from your shed


  • More space will be taken up
  • More likely to freeze in colder weathers

Your water from your house will be connected to the filters. You should make sure that you have enough pressure from your tap. If you do not have enough pressure, it will take a long time to make. If you pressure is low then you can always buy a booster pump which will speed things up.

Once your water is connected to the filters you will have two seperate pipes coming from it. One pipe will be waste water which will need to down down a drain. And the other pipe will be your pure water.

Now that you know how pure water is made here are some reverse osmosis systems that you can use for window cleaning.

Reverse osmosis for window cleaning

When buying your reverse osmosis the most important part is the GPD, which stands for gallons per day. The higher it is the more water will be produced, but the higher the gpd the higher the price.

400GPD Reverse Osmosis with di chamber

The seller of this one, sells these from 50 to 400GPD, but it’s recommended that you buy the highest one possible to produce water quicker.

If you buy this one it is already pre-filled with resin, so it’s ready to use. Out of the box.

Your water must meet this criteria for the unit to operate.

  • be less than 45 degrees
  • mains water pressure 40psi or higher

It’s very unlikely that your property won’t meets these requirements, so there’s nothing to worry about there.

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DI Vessel for making pure-water

All parts of the uk have hard and soft water, and if you live in a area with soft water you may be able to get away with using a DI Vessel. If your water is under 100ppm you should be able to use one. But if you buy one, and it takes your water down to 5 or over you will have to buy a second vessel.

What’s the advantages of using pure water

Spotless results

With all minerals and irons taken out during the filtering process. once you have used pure water, to clean your customers windows. As long as you have cleaned the windows properly the results will be spotless.

Stays cleaner for longer

This one is debatable by many window cleaners, but i also agree that windows stay cleaner for longer when using pure water. From my research i have found that dish soap actually attract dirt, while pure water deters dirt.

Safe for the customers property

Your not using any detergents, so the frames and sills won’t wear out. And no flower beds will get damaged, unless you stand on them of course.


Making pure water is not difficult, once the reverse osmosis is set-up then you can start making water straight away. Also when you are producing your water make sure that it’s being made out of the way of the sun. Either make it in your shed, or if your making it outside store it in a dark tank.


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