Last edited 13 May 2019

Types of water


Approved Document G (Sanitation, hot water safety and water efficiency), 2015 edition, defines a number of classifications of water.

  • Domestic hot water: water that has been heated for cooking, food preparation, personal washing or cleaning purposes. The term is used irrespective of the type of building in which the hot water system is installed.
  • Greywater: domestic wastewater excluding faecal matter and urine. When appropriately treated this may replace the use of wholesome water in wcs, urinals, irrigation or washing machines.
  • Harvested rainwater: rainwater harvested from roofs or other suitable surfaces and collected and stored. When appropriately treated this may replace the use of wholesome water in WCs, urinals irrigation or washing machines.
  • Heated wholesome water: water that, when cold, was wholesome in accordance with the definition (of wholesome water) and has been subjected to a heat source to increase its temperature.
  • Softened wholesome water: water which would be regarded as wholesome for the purposes of the regulations made under Section 67 of the Water Industry Act 1991 (Standards of wholesomeness) as they apply for the purposes of Part G of Schedule 1 in accordance with paragraph (2c) but for the presence of sodium in excess of the level specified in those regulations if it is caused by a water softener or water softening process which reduces the concentration of calcium and magnesium.

The document also refers to:

Other definitions of water types might include:

[edit] Related articles on Designing Buildings Wiki