Small flat replumb, mains & cold water storage tank - which supplies to use?

17 Jun 2016
Reaction score
United Kingdom
Hi All,

I'd really appreciate some enlightenment with this. My wife and I bought a flat which is at the top of a council block and it's in a really bad way and was clearly plumbed and wired by cowboys, we are gutting it and will be re-plumbing it. I'm trying to picture the desired general plumbing scheme.

There is a cold water storage tank in the loft, but we are right under the loft, not so much of a drop.

There is an old riser which contains the soil stack, as well as two vertical water pipes. One branches to feed our kitchen tap, its flow rate is 13L/min and I think this is the mains supply, which goes up to the loft to fill the cold water storage tank. The other pipe I guess comes down from the tank; it branches to feed the bathtub (9L/min), w/c and bathroom sink (5L/min).


We are going to install a gas combi boiler to supply pressurised hot water to the shower and sinks. Should we therefore have the cold inlet to the shower and sinks from the mains supply, to have a similar pressure?

We need to replace faulty stopcocks anyway so I could remove the supply from the cold water storage tank. Is it worth keeping a supply from the cold water storage tank to feed the w/c or anything else?
The flat is really small, only 2 occupants and we won't often be running taps simultaneously. Is there any reason to have a supply from the loft cold water storage tank?

Is it better to have everything( cold water and hot via combi boiler) coming from the mains pipe?
What problems could come from not having the supply from the cold storage tank?
What problems could come from having a shower with hot supply from mains via combi boiler, but cold supply from the cold storage tank?

Thanks in advance for any views and information on this,
Sponsored Links
Go for mains on everything and do away with the storage - it'll keep your pressures balanced at all times that way.
Thankyou muggles!
I like the idea of just using mains, but could there be any advantage to keeping the storage supply, for anything?
The tank will still be up there of course it's for the block, but any disadvantage at all of eschewing my connection to it?
None, barring a post-brexit breakdown of the UK infrastructure leading to rationing of mains water in which case a few hours worth of stored water might be helpful.

Might be sensible, though, to check that you still have your 13 l/min when
there is heavy usage from the other flats.
Last edited:
Sponsored Links
Haha, excellent! Thanks for pointing out that I should check how much variation of the mains flow rate there is at peak times, I'll do so.
I'd also check your lease. Some (a few) prohibit the installation of combination boilers.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local