How to guesstimate mains water pressure?

I think a water tank would need to be 40 metres above the device to create 4 bar of pressure so, unless your mains pressure is unusually high or you live at the foot of a very tall building, you should be ok

Um, given that the subject is "mains water pressure", the height of his tank (if present) is a bit irrelevant.

Tim

Connect the device to the water supply. If this buggers it the pressure is too high.

Bill

You need something like

It has a 3/4"BSP female connector - so will easily screw onto most outside taps or a washing machine tap. Screw it on, open the tap - and hey presto!

If you do that with no water running, that will tell you the *static* pressure. Although probably not needed for your purpose, it may be interesting to see how much the pressure drops when, say, you fully open the cold tap on a bath. If the gauge is fitted as close as possible to where the mains enters the house, this gives a good idea of upstream restrictions in the supply pipe.

Ah yes, the subject line. More than a bit irrelevant then