Would you supply them? (was the real question sorry)
Personally no!
Someone will have to be at home at their beck and call to supply water no matter when they call, unless you instal a petrol pump type arrangement that does cards only (Asda). To provide that over and above your needs you would have to have 3 IBC tanks and a 4040 twin r/o although you could get away with a single. You would need to be changing filters every few weeks.
Expect them to dump you when they get themselves sorted leaving you with equipment that is overkill for your requirements.
If it was a single windie and you could afford a small amount a day then I would have no problem with that.