dazmond heres how i do it,wet the consevavtory with custies own water(using your own hosepipe)scrub away with tfr using the butt on the trolly,then using the hosepipe connected to the tailend(i use hoselock connections for this very purpose)scrub and rinse the roof using their tap water,then put a couple of butts of pure through cleaning the roof and gutters frames glass etc-basicly your working from tfr through to tap water and then to pure thus getting rid of all the tfr first and then tap water working down to pure,so you can then carry on the next job working as normal.sounds confusing at first but works for me