You can use tap water together with a soap or detergent to
clean your windows (although damaging to the environment of course), but if
you only use tap water to clean the windows, the glass will appear milky
white and/or streaky when it dries, and you will be able to write on the
glass surface with your finger. (Try it for yourself). This effect on the
glass is due entirely to the mineral content of the tap water.
Tap water contains dissolved solids, and while this is OK for
drinking, it is of NO use for window cleaning! If you want to wash glass and
end up with perfectly clean windows, all of the minerals need to be filtered
or extracted from the water. This is then called “Pure Water”.
The resin
used in the residential kit effectively removes these dissolved solids in
the tap water and produces pure water. The volume of pure water produced
from one fill of resin is dictated by your local water quality. On average
– one fill of resin will produce just under 300 litres of Pure Water – which
is enough for about 10 cleans of an average 3-bedroomed house.