Water efficiency,
made simple.

Calculate a new dwelling's estimated potable water consumption against the 125 or 110 litres per person per day target. A transparent technical prototype based on Appendix A.

Project & target

Identify your dwelling and choose the requirement that applies to its planning permission.

Site address / project reference

Plot number

Client / applicant

Water efficiency target

125 L/person/day110 L/person/dayCustom target

The statutory Part G targets are 125 and, where applicable, 110 L/person/day. A custom target is an additional project comparison and does not change the statutory requirement.

WCs & taps

WC fittings

Enter each distinct WC type and the number installed. Dual-flush WCs use full and reduced volumes; single-flush WCs use one volume. The calculation uses the weighted average effective flush.

Basin / other taps (L/min)One flow rate or flow:quantity pairs for multiple tap types.

Kitchen / utility taps (L/min)Exclude bath taps, include separate hot and cold tap flows.

Bathing

Shower flow (L/min)Leave blank only when no shower is fitted.

Bath overflow capacity (L)Leave blank only when no bath is fitted.

Appliances & special systems

Washing machine (L/kg dry load)Official default: 8.17 L/kg when no machine is specified. Replace with manufacturer data if known.

Dishwasher (L/place setting)Official default: 1.25 L/place setting when no machine is specified. Replace with manufacturer data if known.

Waste disposal unit installed

Water softener, rainwater or greywater system includedThese require additional Appendix A tables and are not supported by this prototype. Calculation will be blocked to avoid an incorrect result.

How this is calculated

Appendix A Table A1 use factors; Tables A2.1–A2.7 for multiple fittings (including the 70% highest-flow safeguard), rounded component values, 0.91 normalisation, and 5 L/person/day external allowance. Official guidance ↗