The tap water is resumed! Luckily, I didn't need to buy any new parts. But the fix is indeed a temporary hack, which won't last for months. So, it gives me more time to think how to upgrade the system - or, in other words; how to get the money to buy a new pressure tank and related utilities. As, currently the tank is only 25 liters, and I'd like it to be at least twice the volume. Well, but that goes into the waiting list of "problems I will solve as soon as I get the money".