Banging Pipes

[WaterHammer]

Long story short, I living in a lower villa. Since Friday we have noticed water hammer when we run the taps, flush the toilet, etc. Our mains also feeds the flat above and we can hear the loud banging anytime they use their water too.

Had a plumber out who fitted a pressure reducing valve on the cold water feed but it didn't help so he reduced the pressure at the mains (located in the street). This worked, no more banging. However, It obviously reduced the water pressure slightly (still getting 2.5 bar).

Upstairs neighbour has come down to say that their water pressure is now low (they will have noticed a difference but not enough to cause issues). We checked that the valve was fully open and it is. Spoke to the plumber again and it seems there are only 3 options:

1. Live with the reduced water pressure (we could but neighbour not happy)
2. Live with the water hammer (that's a hard NO as it's really loud)
3. Trace the cause.

Option 3 seems like the most obvious, however, the building was built in the 50s and the pipe work goes into the walls. We also have concrete floors so it potentially means ripping the place apart!

Has anyone else been in a similar position? What did you do? Do the neighbours have to accept a slight drop in pressure (as long as it's still within reason) or do we have to accept that we have to get some major work done?

Also, is this a communal issue as the mains feed both properties or is it our sole responsibility as the pipes come into our property?

Any advice would be appreciated.

Ours tend to start banging if there's air in the system. Sometimes it's when the central heating is on so we bleed the radiators to help quieten it. If it's air in the water, info below on what to try.

The easiest fix for this kind of knocking is to first turn off your main supply valve. Make sure you communicate to anyone in your home that you are shutting off the valve as it will stop ALL water coming in. Now, flush the lines by opening all of the faucets and flushing your toilets. Water can still leave your home through drainage pipes and this will ensure all of the supply lines are fully empty.

Once the lines are cleared, feel free to turn your main valve back on. It is important to do this slowly so that the air chambers between and around your pipes have time to refill before the water courses back into them. However, now that the pipes were fully emptied, the knocking sound should be completely gone.

@LovelyGirlCompetition Thank you very much for taking the time to respond. I'll give your suggestion a try!

Thanks again.

Hope it works