Constant use of cold water after bathroom/kitchen renovation???

[dangerdanger123]

I renovated my bathroom and kitchen recently and installed new piping+ faucet + thermostatic mixer and new dishwasher in kitchen, the work was done by a professional plumber.

I have noticed that during the night I use cold water when all the taps are closed( around 9L each day, it has been a month now).

My toilet is not running and there are no visable leaks. We did a pressure test and everything was fine, there is nothing that is leaking.

Any suggestion on where the issue might be located? I suspect my thermostatic shower mixer, that it is doing something funny (like recirculating the water or something of the sort). We also installed a new dishwasher in the kitchen, maybe the issue is there?



The pictures of the cold water meter below have around 5 hours in between them

 

[Gasmk1]

it still could be your toilet most modern toilets now run into the pan so you need to check everything can you isolate certain things like the toilet or new taps on cold side do one at a time over night its a process of elimination. that's just over 2 litres in 5 hours. I suspect toilet at fault what it does is lose water into the pan then tops up but it may not be enough for you to hear way to tell is dry the toiler pan and put toilet paper on the back of pan above water line. if it gets wet there is your problem

 

[Aquarius]

What type of plumbing system? Combi, vented cylinder , unvented cylinder?