8.1 Internal services

8.1.4 Cold water storage

Cold water service shall be provided in accordance with statutory requirements and be adequate. Issues to be taken into account include:

  1. cold water storage
  2. cisterns
  3. cisterns support
  4. warning and overflow pipes
  5. access.

8.1.4.1 Cold water storage#

Cold water storage should be provided with suitable capacity and include primary feed cisterns where indirect water heating systems are installed. Cold water storage should be provided:

  • to supply an open vented hot water storage system (where required by the water supplier)
  • to supply cold water outlets (where not connected to the mains supply)
  • designs should prevent undue consumption, contamination and water wastage.

8.1.4.2 Cisterns#

Cisterns should:

  • be accessible for inspection and maintenance
  • be protected by a rigid close-fitting cover (non-airtight) that also excludes light and insects
  • have holes neatly formed with a cutter in the positions shown in the design
  • be suitably supported.

8.1.4.3 Cistern support#

The cistern bottom should be continuously supported by materials such as:

  • softwood boarding
  • plywood to BS EN 636-2s
  • chipboard type P5 to BS EN 312
  • oriented strand board type OSB3 to BS EN 300, laid with the stronger axis (as marked on board) at right angles to the bearers.

8.1.4.4 Warning and overflow pipes#

Warning and overflow pipes should:

  • be provided at each cold-water cistern, to a suitable external discharge, unless permitted by water regulations where it may be internal if it is conspicuous
  • be adequately sized (19mm internal diameter (ID) minimum)
  • be situated 25mm above the shut-off water level in the cistern
  • be in accordance with water regulations, terminate vertically downwards or be fitted with a horizontal tee where it discharges. And may dip below the water level where permitted by the water regulations.

8.1.4.5 Access#

Access for cold water storage should be:

  • provided to the main roof space and voids that contain cisterns and tanks, etc (not required to roof spaces containing only water pipes)
  • be via an opening (access hatch) with a minimum width of 520mm in each direction
  • not be located directly over stairs or in other hazardous locations
  • include a minimum 1m2 platform located for maintenance purposes
  • have securely fixed boarded walkways between the opening and the cistern or other permanent equipment (boarding should be securely fixed without compressing the insulation).

Last updated: 2nd January 2024

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