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Why do we have a cold water tank in the loft ?

What is the tank for in the loft? It doesn't really make sense to me. Why do we need it? Wouldn't it make more sense to just tee off the mains direct to the bath, toilet, and sink just like we do with the kitchen ?

1 Answer from a MyBuilder Plumber

Best Answer

Hello Joe_443,

There are two types of cold-water systems: direct and indirect. In a direct system, all the pipes to the draw-off points (sink, bath, hand basin, WC, etc) are taken directly from the rising mains or service pipe, and operate under mains pressure. This is usually permitted by water companies for domestic installation in medium to high area, where the supply can provide adequate quantities of water at sufficient pressure to meet the build's needs.

In an indirect system, one point - usually the kitchen sink - is fed directly from the rising mains, which then supplies the cold-water storage cistern. The remaining draw off points are fed from the cold-water storage cistern. This system is designed to be used in low-pressure water areas where the mains supply pipework is not capable of supplying the full requirements of the system. This type of system also has a reserve of stored water in event of mains failure.

So your property is probably in a low pressure area, that is why you have a cold-water storage cistern in your loft. The advantages of indirect systems are that there is:
> a reserve of water should the mains supply be turned off
> reduced risk of system noise sue to lower pressure
> reduced risk of wear and tear on taps and valves, again due to lower pressure
> lower demand on the main at peak periods

Point to note - before 1999 Water Regulations might not have been potable. If your system was installed prior this, then you should get your cistern checked for its ability to keep the water in it wholesome and safe.

Hope this helps.


Answered 2nd Feb 2014

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