help me understand a flats water supply please?

[Theytrytomakmego]

I have reasons for trying to understand this.

It's a flat. There is a pipe that comes off the shared mains, with a stopcock there. It then splits off to the bathroom first, and then to the kitchen.

There is a water meter on that incoming pipe under the kitchen sink.

The boiler is in the kitchen, so I assume somewhere there is a pipe going from the kitchen to the bathroom supplying it with hot water.

Is it possible that the meter isn't recording water coming out of the cold tap in the bathroom?

Yes it's possible if the meter was fitted without properly investigating the system.
You can check by running a bathroom cold tap and watching the meter

Is the flat in a purpose built block or is it a conversion?
If it's done properly then it should be an individual water supply coming in from the street for each flat with its own stop tap and meter.
However historically houses have been converted into flats but the builer has cut corners by not laying in an additional supply stop tap and meter for the new units within the building.

The only way to tell how the bathroom tap is supplied is first to turn it on but leave everything else off and then look for movement on the meter. If that doesn't solve the puzzle then it may be worth asking your neighbours in the block if they can help (it could be going through their meter!)

Thank you both. @Surplus2requirements Can't actually see the meter as the kitchen units appear to have been built around it. There is then a big piece of timber in front of that seems to be connected to supporting the sink unit and a long surface. Trying to disconnect it caused immediate problems, so stopped.

@MrsMoastyToasty It is a conversion. There is a main pipe that splits into several pipes with stopcocks, one for each flat. Lots of corner cutting over time.

Another flat believes they're paying for some of our water. We already don't get on. They are not reasonable people and in a position to cause problems.

I need to be sure they are wrong before insisting on better proof than supplied. If they are right, I need to sort it out without involving them.

Looking into everything, it narrowed down to the only possibility would be if that pipe that splits off to the bathroom first, is not on our meter and is somehow on theirs.

There was previously a water tank and immersion heater in a large bathroom cupboard. I thought that first split off pipe was for that, and the water for the bathroom taps, would be coming from the pipe that also brought the hot water from the boiler in the kitchen?

The meter was fitted a long time ago, after the bathroom water tank and immersion heater had been replaced by a combi boiler.
I think some pipes involving the water tank/immersion heater got buried in plaster when the cupboard was then opened up as part of the bathroom.
Later the kitchen was fitted, leaving no access to the meter.

I am wondering if it is possible this first pipe also fed the bathroom sink (and maybe bath) cold tap and they have somehow capped the supply to the old water tank, but not to the bathroom sink?

I am now looking for the least damaging (or cheapest) way of finding were the water from the bathroom sink tap actually comes from, as it seems that pipe is either the culprit, in which case we need to get it run it of the kitchen supply.

Or, cold water to the sink is already supplied from the kitchen along with the hot water. If it is then all our water goes through our meter, and they're wrong.

Do you have a shared water tank in the loft?

I live in a purpose built block and we have this arrangement (minus the water meter as Thames Water deem us to be unable to have a meter fitted due to the aforemntioned arrangement).

So our kitchen supply and supply to the combi boiler come straight from the mains and there is a stop cock under the kitchen sink. The cold tap in the bathroom sink and the toilet are supplied by a communal "gravity tank" on the roof and there is a second stop cock behind an inspection panel between the toilet and the sink.

Ginmonkeyagain That is an interesting set up. Thank you.

I don't think there is a gravity tank anywhere above us. Where the loft was is now part of two flats. But I will try asking the people at the top.
If here had a panel and second stopcock, it would have to be behind the bath.

I know we, and the people complaining, have meters. That suggests there isn't a gravitytank known about, going off your metering situation, as we are metered.