How to get it right: Domestic water usage for new dwellings

The building regulations specify limits on water use for newly constructed homes and those formed by converting existing buildings. Water usage from WCs, wash basins, sinks, showers, baths, and white goods such as dishwashers and washing machines are all included in the requirement.

English regulations

In England, the regulations require that the average water usage be no more than 125 litres per person per day unless the planning permission for the home has specified that this needs to be reduced to 110 litres per person per day. The planning permission will state whether this standard has been applied. It's important that the person submitting the application for building control approval with full plans informs the local authority building control department of this planning requirement.

Estimated water usage needs to be calculated unless the water fittings used follow the guidance in tables 2.1 and 2.2 of Approved Document G (England).

Table 2.1: Water fittings route for 125 litres per person per day standard.

 Table 2.2: Water fittings route for 110 litres per person per day standard.

Where the water fittings to be used exceed the consumption stated in the tables or where a shower is not to be provided or where a waste disposal unit, water softener or water re-use is proposed the estimated water usage should be calculated using the method contained in Appendix A of Approved Document G. 

Welsh regulations

In Wales, the regulations require that the average water usage be no more than 110 litres per person per day for new dwellings and 125 litres per person per day for dwellings formed by conversion of an existing building.

The estimated water usage needs to be calculated unless the water fittings used follow one of the performance standards in table 2.1 of Approved Document G (Wales). 

Where the water fittings to be used exceed the consumption stated in the tables or where a shower is not to be provided or where a waste disposal unit, water softener or water re-use is proposed the estimated water usage should be calculated using the method contained in Annex 2 of Approved Document G.

What your building control team will need to see

Building control in both countries should be provided with water efficiency calculations at the design stage where a fittings approach is not followed. Any changes to the fitting’s specification should be included in an updated calculation and resubmitted.

Your local authority building control authority will need to be issued with a notice within five days of completion of the home stating the potential water consumption. They should also be provided with a final version of the water efficiency calculation at the same time.

Disclaimer:  

Every care has been taken to ensure that the above content is correct at the time of publication.  Any reliance on the content should be verified by the dutyholder(s) and their professional advisers.  It is the responsibility of the dutyholder(s) and/or person carrying out the work to ensure compliance with the relevant building regulations and associated legislation.

This content is given in good faith by LABC.  It is not definitive, and compliance will be a matter for the relevant building control authority to decide as the enforcing body for the building regulations, and ultimately for the appropriate tribunal or court to determine.  

LABC – Application and use of Member Guidance Notes   LABC is a membership organisation, providing guidance and support to its member local authorities around England and Wales. LABC is unable to comment on the application and enforcement of the Building Regulations or other building safety related legislation to a particular proposal, as this is a matter for the local authority in whose jurisdiction the building work is being carried out or, in the case of High-Risk Buildings (HRBs), the Building Safety Regulator (BSR) and for the courts to rule upon.