Why turn water off
upstairs i wipe brush over with flow on , then with flow off, the drips from upstairs sills then stop quicker,
i also make sure all the crap is removed from the gap between sill and frame on first cleans,
i still find esp. on sills that get quite dirty between cleans, that if you wipe sill with flow on , some bits wash back into gap , then run onto sill when you move.
down stairs sills i also have a cut down squeegie , i go over all downstairs sills with this, takes seconds, and looks better than leaving downstairs sill wet.
daz