The Process - Water to Pure Water


The Process - Water to Pure Water
How it works - A bit about the water purification process (It's as close to rocket science as we will ever get!)

When we talk about Pure Water or RO (Reverse Osmosis) water for window cleaning, we are referring to the process we use to transform normal tap water into Pure Water, ready to be used for your window cleaning. Many people think when they see window cleaners using the extendable poles to wash windows they are using tap water. We're not though, it's no wonder why people see no reason why they couldn’t do their own windows with a long pole and a hose. It's not that there is anything wrong with giving windows a wash using water from the tap but it’s unlikely to produce the same exacting results that 4-Seasons Cleaning are able to produce because all our water is purified through a series of filters to produce Pure or RO water.

Rubbish In - Rubbish Out (RIRO)
Purifying water for cleaning windows makes it far more effective as it is 'cleaner' effectively making dirt stick to it and then simply run off the window during the rinse stage of our cleaning process. This science happens as water in its purest form absorbs pretty much anything it contacts. It's probably no surprise to you that tap water has been found to contain over 300 different man-made chemicals along with various organic matter and bacteria. When Pure Water is applied to your windows the dirt, dust and other particles will simply be sucked up by the water when brushed over the glass and then run down the window when we rinse it all off.

Water in its purest form cannot be consumed as it would dry your mouth because it absorbs all of the bacteria. As an example of what can be found in normal tap water; think of when you have seen a leak from a pipe. There is normally a build-up of encrusted limescale which is one of the minerals found in tap water. This never evident in Pure Water as it's removed at the very first stage. Hard or soft water areas will normally have a range of dissolved solids in the water - somewhere between 275 to 375 Parts per Million (PPM). When water is purified the total amount of dissolved solids in the water is 0.00.

It's not magic (but you'd think it was)
This major part of this process takes place at our base where we pressurise the tap water and then pump it through the following series of filters to produce 100% pure laboratory grade water.

1st Stage – Water softening
After the water has been boosted up to pressure it passes through the first stage which is an ion-exchange vessel to soften the hard water and make it easier to pass through the next 4 stages of filtration. This process is to help protect the main RO membrane by removing elements like calcium, magnesium and other minerals in the water which would usually cause limescale. After the water has passed through the softener, it’s ready for the filtration process.

2nd Stage = Sediment filter
Water is still pumped at high pressure and flows into the sediment cartridge to remove any suspended solids. It acts like a very fine sieve to remove micro particles that are found in tap water up to 1/300 of the size of a human hair. Anything smaller than 1 micron will get through and reach the next stage of the process.

3rd Stage = Carbon/ Charcoal Filter
The next stage of the process before the water even reaches the RO membrane is the carbon or charcoal filter. The water once passed through stage 1 enters a second pre-filter which removes microscopic sediment under 1 micron, chlorine, fluoride, bacteria and other organic compounds found in unprocessed water. It works using a process called adsorption where the pollutants are trapped inside the pore structure of the carbon substrate, the same process as found in respirator masks or gas masks but with air passing through instead of water. Just one pound of activated carbon is the equivalent to surface area of 0.15 of a square mile or 100 acres, so very absorbent.

4th Stage = Semipermiable membrane or RO filter
This is the most important stage of the water purification process as this is where the water entering the filter is still around 210 PPM, and when it come out as pure water it is around 25 PPM. The RO filter is a semipermeable membrane nearly 1 meter long that allows pressurised pure water to pass through it and be collected from one outlet, while it captures any impurities left from the first few stages in the second outlet, ready to be discarded as waste. The RO filter is the most important element in the production of pure water with some companies opting to have it fitted in their vehicles. This allows them to plug a hose pipe in and fill up their on-board water tank (probably at your and other customer’s expense.) It's a long and slow process relying on mains pressure and can limit the time an operator can work before needing to fill again. We process into our own holding tank and can transfer to our vehicles in about 5 minutes!

5th Stage – Water Polishing
Once the water has been passed through the softener and three stages of filtration it is nearly pure and ready to use. At this stage it is around 20-30 PPM and needs 1 more process to make it 100% pure, this stage is called polishing. The water is passed through an 11 Litre De-ionising (DI) Vessel containing a resin which removes any final impurities in the water and takes the PPM down to 0.00 before transferring it into our sealed holding tanks, ready to be used to clean your home or business.

6th and 7th Stages - The Cleaning Process
When we arrive at your home or business we will usually be carrying a large amount Pure Water in our vehicle's holding tank. This is pumped from the vehicle through another on-board DI polishing vessel into a heater and along the hose and up to the head of the pole we use to clean windows. As part of our service we also clean your window frames too. This prevents the dirt that has built up on them making its way back onto your clean windows next time it rains. This is one of the ways we help you to keep your windows cleaner for longer and improving the appearance of your home or business.