[Apple Roof Cleaning]

Lots of good advice already given here.
If you are going to use the customers water supply, you might want to look at 3/4 inch Mean Green Hose as a water hose only.
3/4 inch Mean Green is lighter, and easier to handle then most 5/8.
It gives more flow because it is bigger, and cuts rinse time down a tad.
Like David said, you will need to explore your local market to see what to charge.
Good Luck to you!