Water pressure is often referred to as “head” or “head of pressure” relating to the highest point of the source of water.
Example; a 10 metre high column of water would produce a pressure at the base equal to10 metres head.
10 metres head is equal to 1 bar of pressure.
Low pressure tank fed systems in houses generally work at 0.5 bar or less, even as low as 0.2 bar on the first floor.
High pressure systems are often limited to 2.1 to 3 bar pressure.
Mains water entering the property can vary from 1 bar to as much as 8 bar pressure.
Note: Don’t confuse good pressure with a good flow rate, you can have high pressure but with very little flow if pipework or taps are blocked.
On high pressure plumbing systems you need a combination of high pressure and high flow rates.