8.1 Internal services

8.1.4 Cold water storage

Cold water storage 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. cistern 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)
  • to 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

Also see:

7.2.12

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
  • be located for maintenance purposes.

Boarded walkways and working platforms should be securely fixed with a minimum clearance of 50mm between the top of the insulation and the underside of the walkway to ensure a clear ventilation space.

Last updated: 2nd January 2025

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