Connecting to Rising Main

Well into the refurbishment of my sons' flat but I have come across something that puzzles me. My own property has all the cold water to the taps supplied direct from the rising main.

This flat has the kitchen tap supplied by the rising main but all the other cold outlets are supplied from the cold water tank in the loft. The rising main supplying the cold water tank goes via the bathroom where the basin tap and toilet are, so why aren't these just run off the rising main adjacent.

As I am changing the bathroom into two bathrooms is there any reason why I cant just take the cold water off the rising main? The showers are supplied from pump that obviously is fed from cold tank in loft to equalize pressure from hot cylinder.

Tank fed cold to the bathroom was the norm many years ago.
Maybe someone else can suggest the rationale for that and reason for the change.

Yes you can probably change over to use the rising main. Is the mains pressure generally good?

Many thanks for coming back so quickly. Whilst the rising main pressure on a third floor flat is not brilliant at times it is far better than the pressure from the cold storage tank, it would also be quieter in the middle of the night!!

It's the variability of the pressure you might need to worry about; the pressure from the tank will be constant (but low) while the mains can vary depending on time of day etc.

I don't have much practical experience to share though - hopefully someone else will comment.

The reason would be mixer taps and showers needing balanced pressure, nowadays if it's all off a Combi then it's all at mains pressure anyway.
You can get condensation all over your toilet cistern if you use the mains feed too.

dolph said:

As I am changing the bathroom into two bathrooms is there any reason why I cant just take the cold water off the rising main? The showers are supplied from pump that obviously is fed from cold tank in loft to equalize pressure from hot cylinder.

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Both the feed to the hot cylinder and the cold supplies to the shower,taps and toilets are probably from the same tank. I would expect t see that the pump is pumping both hot and cold.

If you switch the cold supply to mains then you are likely to end up with unbalanced feed - this will lead to problems with the shower(s)

This assumes that you have a 'traditional' set up.

It might be worth you posting the arrangements for that you have for heating the water just to clarify.

Thanks to all of you for replying. Newboy this is the present set up :- Rising main enters property on 2nd floor, feeds the kitchen sink tap, then continues upstairs to 3rd floor "utility room" where the cold water tank is situate, where it terminates filling it with a ball valve. It goes through a concrete floor to the third floor and via the adjacent bathroom to get to "utility room".

This cold water tank is a very old original galvanised split into two square tanks, one a large tank that feeds to basin tap and toilet situated next door in bathroom, it also supplies the hot water direct cylinder that is situated on the second floor directly below the "utility room", finally there is a separate feed off to a Stuart Turner shower pump which is underneath the cold tank. The hot feed to the shower pump comes from separate feed from the hot water cylinder that is heated by immersion heater.

The small cold water tank part of the split tank is the header tank for the gas central heating.

As part of the refurbishment the galvanised tank is going, replaced with plastic cold tank in loft, hot water tank moved to "utility room". New central heating boiler system being fitted to heat water and supply vented heating system (poor mains pressure at "busy" times in 20 flats precludes unvented system). The plastic cold tank will supply hot cylinder and shower pump and could supply taps and toilets in the two new bathrooms being created the subject of my question

My original question was, as rising main cold water supply will go through these two new bathrooms to reach the plastic tank in loft can I tee off to supply taps and toilets in these bathrooms, thereby obviating the need to provide separate feed to these from tank in loft. The "busy" times pressure to these two appliances is of little consequence.

This will have two advantages, firstly to save a separate feed from plastic tank to supply taps and toilets, secondly at present situation when the toilet is flushed in the middle of the night (these are two sociable 30 year olds!) two ballcocks operate double the noise! Pressure is very good then.

endecotp said:

Maybe someone else can suggest the rationale for that and reason for the change.

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As mentioned steady ( albeit low ) pressure. Low pressure is better for taps, they last longer before the washer / ceramic needs replacing

Continuity if the mains flow ceases or due to peak demand drops to a trickle.
Fill the tank over night and use it during the day was the way for people lving at the top of a hill coped.

Reason for change ? Flats and houses without loft space created the need for direct on line systems and combination boilers. These were hyped as "the modern way" and people were convinced that "modern" was best when in many cases it is the worst way

dolph said:

poor mains pressure at "busy" times in 20 flats precludes unvented system

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If there is a drop in performance then there is a case to look into a whole house pump but if the mains to the building can't cope at the moment that may not be an option.

I would keep it as is, make sure the new cold water storage cistern is kept clean and sealed and insulated and it will be able to deliver what is classed as wholesome water. Especially if the new bathroom basin(s) will be using mixer taps then a balanced supply is key, as @ newboy mentions, so running the cold from the mains may alter that and you could have problems.

Thanks to all that replied I am very grateful, as always. I have decided to stick to the existing set up and as the cold tank will now be 5/6 feet above the taps, the pressure should be better.

As the cold outlet from the cold tank in question will be in 22mm pipe, could I get away to feed the taps and w/c's with 10mm plastic pipe from a four outlet manifold as none of the taps/wc's are more than 6 feet from it, I would propose doing the same with the hot water to balance. This would make feeding the pipe to the outlets so much easier with no "hidden" joints.

Don't even consider for one second using 10 mm pipes on a gravity fed plumbing system where the header tank is only 5 or 6 foot above the taps.