Water mains high or low pressure

[ss]

I know it may sound obvious but I am going to replace the ballcock/valve part in the main water tank in the loft as they are cheap enough, but having a look at them today they are marked high & low pressure. I assume for the main water tank it would be a high pressure one. The water comes in to the house under the kitchen sink from outside and then up to the loft. The water is turned off under the kitchen sink so I am assuming the main tank is mains pressure.

So high or low?

[The Natural Philosopher]

depends on your area. Mine is reasonably high. many bar I think.

[John Rumm]

High in all probability. The low pressure ones are more commonly used for gravity fed cisterns. (unless these are specifically marked for high and low pressure *mains* use)

[ss]

Thanks for replies as the main tank is mains fed and we appear to have good pressure but havent a clue what that pressure reading is, its sounds like high pressure is the best bet.

[The Natural Philosopher]

Generally 'low pressure' means 'optimised to actually work at all with a

6 foot head'

Everything else is 'high pressure'

[Roger Mills]

It's the safest! If it works - fine. If you get insufficient flow into the tank, change it for a low pressure nozzle.

If you fit a low pressure ball-valve on a high-pressure supply, it may not turn off properly, and may overflow.