For windows i cant do

i have just got one of these Water Fed Pole 18L Backpack and Impressor Glass Fibre Pole for windows i cant do with a ladder how do window cleaners get there water or where from?pure water

You either produce it yourself with a Reverse Osmosis unit or if you have a local pure water seller near you.

I live in a hard water area (not on a water meter) so best solution for me was to setup a static ro/di system that goes into 1000 ltr ibc holding tanks. Then when needed I just pump the purified water into containers or van tanks.

The main benefit of producing pure water from a static setup at home for me is I can still produce pure water whilst out working.

To get a decent high volume RO/DI setup like a 4040 ro will set you back a few quid but are far quicker to produce pure water if you are on a water meter. Unfortunately good wfp gear is not cheap as you will find out.