Save your 25 litre chemical containers.
When going to a job with awkward to get at water supply, fill a few of them up at home (hot water) just before you go. It will only take a couple of them to give you a full tank of water, takes about 30 seconds to fill your machine!
Very useful if machine is to be left outside, and water supply is perhaps upstairs or the other end of the house.
Might not sound like it, but when on a "rush job", working against the clock, it makes all the difference.
Cheers
Chris