The water here comes from a well, not from the mains. It refills on its own, but slowly — and when it's used faster than it gathers, it runs out for everyone at once. The boiler also draws electricity to heat it.
The method above is called a navy shower — it's how sailors wash at sea, where fresh water is counted. It isn't hardship; it's simply the water off during the minutes you don't need it anyway.
A dripping tap loses over 10,000 litres in a year. If you hear one, tell us.