The term Pure Water in window cleaning describes ordinary tap water that has been filtered through a purification system, to remove all the natural minerals. This water is often described as ‘deionised water’ due to the type of filtration used. This is explained further HERE. The reason for this is that pure water dries to leave a completely crystal clear finish, as opposed to general tap water that dries to leave minerals on the windows, which is the reason for hard water stains and unsightly white spotting.
When applied to Window Cleaning, using pure water means that there is no need to squeegee the water from the window. Providing you have agitated (scrubbed) the dirt and rinsed the window thoroughly, you can leave it wet!
Pure Water Systems come in varying capacities, from many different brands & to fit any need & budget.
For aspiring commercial Window Cleaners, the added safety benefit of cleaning from the ground is an excellent selling point, and even a requirement for some buildings.
Regardless of your preferred method of cleaning Windows, the smart modern Window Cleaner will have a means to utilise purified water, even if it is not the primary method of cleaning.
In addition to Hydrogen & Oxygen (H20), tap water also contains minerals. For drinking purposes, this isn’t a problem, however when it comes to cleaning, the likes of calcium, magnesium and other minerals remain when the water evaporates away. This leaves hard water stains and unsightly spotting. You’ll notice these build up on any glass surrounding showers or taps at home, or even after washing your car.
Generally water is classified as either hard or soft. This refers to the amounts and types of minerals built up in the water, the harder the water the more costly it is to purify, and this is usually location dependent. For example in the U.K most of South Wales & Scotland have soft water (TDS readings of 150 or less), whereas Bristol & London have very hard water (350-500ppm in places). To find out which purification method suits best, click HERE).
You can test your tap water with a TDS Meter which measures electrical conductivity and produces a value indicating the level of dissolved solids (minerals) in the water. For window cleaning purposes, a value of 000ppm (parts per million) of dissolved solids is considered pure and will produce a streak and spot free finish on the glass. It’s reasonable to effectively clean windows with readings of 0-7ppm, though this is just a rule of thumb, you may be able to clean with readings higher than this depending on what specifically is in your water. Trial and error will help you determine where the line is drawn.
HM Digital produce a high standard of TDS meters, and are regularly available from approved suppliers, you can pick one up HERE