Every year we get a panicky topic about this.
Hose pipe bans DO NOT AFFECT COMMERCIAL ACTIVITY such as window cleaning.
Only drought orders can interfere with commercial use, and even the it has to be stage 3 (the worst stage)
If we get to a stage 3 drought order, there’ll be queues for water at standpipes in the street. Even if you could use WFP in that instance, I’m not sure I would. You would risk enraging the local populace (including customers).