Part G Water Efficiency Calculations

Part G of the Building Regulations limits how much water a new home is designed to use. Building control needs a calculation for every new dwelling before completion. We produce it from your fittings schedule and tell you which fittings to change if it does not meet the target.

The targets:

125 litres per person per day. The standard for all new homes in England.
110 litres per person per day. The tighter optional standard, which applies where a planning condition asks for it. The London Plan and many councils in water-stressed areas require 110.

Check your planning decision notice. If there is a water condition, it says which figure applies.

How we calculate it

We use the government’s water efficiency calculator. It takes the flow rates of taps and showers, the flush volumes of WCs, the bath capacity, and the water use of the washing machine and dishwasher.

What we need from you

The sanitaryware and appliance schedule, with make and model or the flow rates and volumes
The number of each fitting in each home
The planning condition, if there is one

Turnaround: 5 working days once we have everything we need.

Changes coming

The government has consulted on a lower limit for new homes. At October 2026 no change has been confirmed. We apply the figure in force for your project.

Why are Water Consumptions Calculations required?

Approved Document Part G of the Building Regulations mandates that all new dwellings, including conversions, must have a water consumption rate of no more than 125 litres per person per day. Compliance is demonstrated by submitting a water efficiency calculation to Building Control at both the design stage and upon completion.

In addition to the national requirement, local planning authorities may impose stricter sustainability conditions, requiring a reduced water consumption rate of 105 litres per person per day. This often forms part of a planning condition for new developments.

Water Consumption Calculations

At EPS Group, we take pride in building strong, collaborative relationships with our clients. Our team provides expert customer support and technical consultation, delivering cost-effective and practical solutions to ensure compliance with Part G of the Building Regulations.

We offer water efficiency calculations within 24 hours upon request, with expert guidance to guarantee compliance with both Part G and any additional planning requirements.

For more information about Water Consumption Calculations or to discuss your specific requirements, please call us on 0208 908 5141 email us at info@quodox.co.uk