Not sounding like water hammer noise. Sounds like air vibration. Do you have subfloor vents? Is it worse when windy. If so builder. Do you have ducted heating or cooling?

Hi both, thank you so much for taking the time to respond.

I've bleed all the waterpipes, however in the evening the sound was back, just like other days.

What kind of puzzles me is that the noise occurs at night, and at the start of the day.
Winds during the day and night don't change the situation.

@Kate, yes we have a subfloor and vents. We don't have ducted heating or cooling.

Also another update, I have just turned the main power off to the house, the sound still occurred, so not electrical related I think?

We'll get closer and closer :), again, thanks for your help..!! If there is anything else we can do, we can use all advise!

Have you turned the water off at mains and then listened? Sprinkler? Leak underground? Night time is often quieter so easier to hear

Check your water meter to see if you have a leak. We had one underground and the water was not coming to surface for 40 metres.

We tracked it down by noise

Hi Malcolm and Kate, Thank you both so much for your input. This is so helpful... we will investigate the options you put forward and get back to the post.

Thanks again!!!

Reinier

Hi, me again :), thanks for your comments so far, I feel we're getting much closer with your help.

Just a few updates:

Drainage vent pipe: I put my ear against it, and I could not hear anything vibrating while inside the house the sound was quite loud.

I turned mains off as Kate advised, this stopped the vibrating immediately. After turning the mains back on and opening and closing 1 tap, the vibrating returned instantly.
Putting my ear against the water pipes, (hot water I hear nothing), (cold/normal water I do hear the vibrating through the pipe).

Currently assuming it's our copper water pipe, vibrating when under pressure.

Could this be caused by water pressure that's too high?

What else could we test before calling in professionals?

Bleeding the system yesterday did not seem to have solved anything.

You could try turning the mains tap down a bit and see if it helps

Thanks Kate, that is something we can try! I ordered a water pressure gauge to test if the pressure from the mains is indeed the cause.

Either turning down the mains or we will install a PLV, it just still puzzles me why the vibrating occurs increased over the evening even during warmer nights like this week.

Perhaps one of the fixings is getting looser. Might be time to call plumber

The plumber installed a plv, our waterpressure was a little high. Still 5% vibration left, so will need to fix one of the water lines, however problem solved.

Thanks all for helping out!