Cold Water Storage Tanks And Accessories.

It provides a reserve of cold water and, in vented systems, the head of pressure that feeds the hot water cylinder and cold taps. It also buffers supply against mains interruption.

In modern unvented and combi installations there is no cistern, since everything runs at mains pressure.

Yes, and a properly fitting one. Byelaws require storage cisterns to be covered to keep out light, insects, dust and vermin. Light encourages algal growth and contamination risks are real.

Vents and overflows should be screened for the same reason, and the overflow must discharge where it will be noticed.

For domestic vented systems, capacity is usually matched to the hot water cylinder plus a reserve — 227 litres (50 gallons) is a long-standing standard for a typical house.

Oversizing has a downside: water that sits for extended periods deteriorates, so bigger is not automatically better.

On a continuous, level platform that supports the full base, not on joists alone. A 227 litre cistern weighs over 230kg when full and will distort or split if it spans unsupported gaps.

Boarding across joists, sized to distribute the load, is the standard approach in a loft installation.

In a loft, yes — the tank, the lid and all associated pipework. An uninsulated loft cistern is a common cause of burst pipes and frozen supply in cold snaps.

Do not insulate the loft floor directly beneath the cistern, as residual heat rising from the house helps keep it from freezing.

Inspect annually and clean and disinfect when the inspection shows it is needed — typically if there is sediment, biofilm, debris or evidence of insect or vermin ingress.

A well-sealed cistern with a screened vent needs cleaning far less often than an open or poorly covered one.