why would you want to buy your water if you have a tap.dose not make sense
Perhaps he lives in a flat, has no space, difficult neighbours / landlord, low water pressure, meter, cannot park near his home etc. etc.
I live in a flat, used to produce own water but would spend hours of an evening trying to gain a parking space close enough to fill my tank that then would take 2-3 hours to do. could never really be sure or able to plan a full working week (some days I could not even park in same street). Now I buy my water, my working day is shorter, I can plan and schedule days ahead and have my free time back again.
So it can make sense.