I'm no concerned about this when it comes to my every day residential work. I just hook to each house. But I may have a small commercial job coming up that has no water source. And I would like to expand into smaller commercial in general. So I'm just thinking ahead to cover those bases.
I'm currently using a 35 gallon on my 5.5 gpm. Yes, you read that right, lol. 98% of the homes we do cohabitation siffucient water flow to feed the machine directly, so my tank stays filled the whole time. But on occasssion, we come across a house with a well or just low flow of water. So with those, we have to stop every now and then and let the tank fill back up. But overall, it's not a problem. But I can't do anything with a 35 gallon tank if there's no on site water source.