My downstairs neighbour gets priority on the water?

[scots lass]

I live in a converted flat on the first floor. It has a traditional plumbing system with hot water tank (small, and in my kitchen), boiler and cold water tank in the loft.

Whenever my downstairs neighbour flushes her toilet or turns on her cold water mines stops.

e.g. if we both flush our toilets at the same time, my cistern doesn't start filling up until hers has filled

Also - sometimes the cold water tap stops completely if she is drawing water for washing machine etc...

This happens both in the kitchen tap (which I would have thought came from the mains) as well as the bathroom tap and toilet (which I would have imagined came from the tank in the loft)

How can I stop this happening? I'm worried it will affect my washing machine pump eventually, and is just a general pain! I'm sick of being second best!

 

[Bahco]

It sounds like you have very poor mains pressure as water will always travel the easiest route.
Try checking the stoptap is fitted correctly (with arrow facing the flow) and if it is opened fully.
Contact your water company for a check as they have to provide minimum pressures.

 

[ChrisR]

It's only the water co's responsibility to provide a meagre pressure at the communication pipe - that's where it comes into the curtelage of the property.
If someone decides to convert a building into several flats, he should get a new mains riser for each one, but many don't.

The mains may be at a pressure of say 2 bar - that means it will go up a (approx) 20 metre pipe, so everynody gets water if they're the only outlet. But if someone opens a big (or sometimes even small) tap, the pressure at that tap connection to the mains pipe would go right down, to maybe 0.2 bar. That will only rise another 2 metres - so you don't get any.

If the single pipe were very fat, it would supply the tap's flow without such a big drop in pressure, but they're all probably the original 1/2" / 15mm

 

[stanrog]

Taking that you assumptions are right re mains supply for kitchen and cold water tank for bathroom tap and toilet, poor mains pressure as mentioned by others covers your kitchen. For the bathroom and toilet
my reading of your problem is that both flats could be on the same cold water pipe system fed by the tank in the loft. and that the pipe size is inadequate or otherwise has the flow restricted by a stopcock/value.

 

[scots lass]

So - how would I go about solving it?
Sounds like I need to check if there are two cold water tanks in the loft (however I'm sure my downstairs neighbour has a condensing boiler, which surely means she is not using a cold water tank?)
I can hear a tank filling however after she flushes her toilet
Is this a large job to fix? I'm assuming the water company will not do anything as its only their job to provide water pressure to the house - not their responsibility if that has been converted to flats?

 

[stanrog]

My solution would be to run a new cold feed from the tank, to connect to your existing pipework at the point of termination of the connection to the current cold feed (supplying both flats). This would ensure that your supply is independent from the flat below.
In plumbing terms this is a straight forward job and no more than a mornings work and that is being generous, however this is not to say that complications could not arise.