absolutely no idea, but seriously, when i used to use a wfp 7 years ago, i once forgot to ro one night so just filled tap water as it was only council work, soaped and rinsed, let em dry, just a few spots, so the ro unit got sold, and i carried on using tap water for 3 years, not a single complaint, in fact they were chuffed as no ladders used. don't get me wrong, they were not perfect, but good enough.
i have trailer, technical expertise and access to recycled blue tank 45 gallon tubs. we already have an unger big pole,
but seeing on that we plan to do our work for next couple decades, might aswell cut down on the really high climbs.
as i said there is only one window, well two on one house style but previous wc didn't touch that as its above a bay and that would be a mega dodgy climb, so if i can clean that aswell, bonus, i look good, but like i said only small amount of work so wouldnt want to spend more than £400 to £500 between us.
cheers