Cold water supply to a bathroom washbasin in a modern purpose-built flat

Idomeneus

I refer to modern purpose-built flats - built within the last 35 years, say.  How common is it, in this type of accommodation, for the cold water supply to a bathroom washbasin to come indirectly through a cold water storage tank?  Or is it far more common for the cold water supply to come directly from the mains?

Have there been any changes in the law, building regulations, etc., during this period of time, that affect where the cold water supply to a bathroom washbasin must come from?

I presume that the cold water supply to a kitchen sink must always come directly from the mains?

The background to this query, in case of interest, is that my wife and I would like to buy a modern purpose-built flat and we would like to ensure that the water from the cold tap on a bathroom washbasin is fit to clean our teeth, rinse our mouths, or even drink.

ThisIsWeird

Hi Ido.

As you say, the cold kitchen tap supply will be direct from the mains as it needs to be potable.

I'm not aware of any changes to any regs that would oblige the other cold taps to also be direct from the mains, but I would suggest that - in a flat of any type - the chances are that it will be. But there could/will always be exceptions.

Due to the nature of most flats - that they don't have a loft space - the trend is to have a mains-powered water system. This will likely either be a 'combi' boiler, or an unvented, pressurised, hot water cylinder. Neither have the need for a cold storage tank, so all the cold taps will also be supplied direct from the mains.

Exceptions to this will tend to be found in older properties that haven't been updated. These could have a CWS (cold water storage) tank in a loft, possibly even a large shared one that supplies more than one flat, or you will sometimes find a smaller CWS inside the flat itself, often mounted above - or as part of - the hot cylinder, but these deliver such poor water flow rates that it's a rare find these days.

Just add this Q to your list of Qs before any viewing! Chances are you'll like the answer

Idomeneus

Great answer, thank you.

I'm not a plumber or a central heating engineer but I did know that combi boilers and system boilers require neither a cold water storage tank nor a feed and expansion tank.  So, in a flat with one of these types of boiler, I would have expected all cold water taps to be supplied directly from the mains.

I'm a little intrigued about how the use of water can be metered if there is a shared cold water storage tank.  Does anyone know the answer?    

35har1old

Idomeneus said:

Great answer, thank you.

I'm not a plumber or a central heating engineer but I did know that combi boilers and system boilers require neither a cold water storage tank nor a feed and expansion tank.  So, in a flat with one of these types of boiler, I would have expected all cold water taps to be supplied directly from the mains.

I'm a little intrigued about how the use of water can be metered if there is a shared cold water storage tank.  Does anyone know the answer?    

Is there a meter fitted 

Section62

Idomeneus said:

I'm a little intrigued about how the use of water can be metered if there is a shared cold water storage tank.  Does anyone know the answer?    

Each flat could have a meter installed internally, but in reality properties of this type are probably unlikely to be transferred to metered billing and instead will remain on some form of assessed charge.

Bear in mind that the hot water being heated by a combi or unvented cylinder is not a guarantee that all cold taps in the property will be mains fed.  I agree with ThisIsWeird that in modernised flats it is more likely all taps will be mains fed, but if it is important to you that the taps are mains fed (e.g. potable) then this needs to be tested rather than assumed.  The lack of a need for a CWS with a combi or unvented cylinder doesn't rule out the possibility a CWS is installed and in use for one or more cold water outlets, especially with an older but modernised property.