Water Efficiency Calculations – Part G

Professional Water Efficiency Calculations for New Dwellings

We provide fully compliant Water Efficiency Calculations in accordance with Part G of the Building Regulations (Requirement G2) for new-build homes, conversions, and residential developments across England.

Our reports follow the official BRE Water Efficiency Calculator for New Dwellings, as required by Building Control and local planning authorities.
All calculations are completed accurately and delivered in a council-ready format for planning and building regulations submissions.

Whether you’re an architect, developer, planning consultant or homeowner, we ensure your project meets the mandatory 110 litres per person per day or 105 litres per person per day targets (depending on your council).

 
What Is a Part G Water Efficiency Calculation?
Under Part G of the Building Regulations (Section G2), all new dwellings must demonstrate that water use is limited through the specification of efficient fittings and appliances.

Our assessment uses the BRE-approved Water Efficiency Calculator, which measures total daily water consumption per person by evaluating:

Taps (flow rates)
Shower flow rates
WC flush volumes
Bath capacity
Kitchen and utility appliances (dishwashers, washing machines)
Greywater systems (if applicable)
Rainwater harvesting (if applicable)
We produce a full Water Efficiency Report showing compliance against:

110 L/person/day standard (national baseline)
105 L/person/day requirement (tightened requirement by certain councils)
 
When Do You Need a Water Efficiency Calculation?
A Part G Water Efficiency Report is required for:

All new-build dwellings
Flats and apartments
Residential conversions (where fixtures/fittings are changed)
Permitted development homes
New extensions creating new dwellings
Planning conditions compliance
Building control sign-off
Many councils require the calculation before planning approval or as a pre-occupation condition.

 
Council Requirements
Increasing numbers of councils now request a Water Efficiency Calculation at planning stage or before discharge of conditions. Requirements vary:

Most councils require:
110 L/person/day compliance via standard Part G target
BRE-calculated Water Efficiency Report
Specification of all fittings and appliances
Evidence that installed products match the calculation
Some councils (especially high-growth areas) require:
105 L/person/day enhanced target, aligned with:

Local Development Plans
Sustainability policies
Water scarcity zones
Councils frequently requesting Part G reports include:
Greater London boroughs
Cambridge, Oxford, Milton Keynes
Bristol, Reading, Southampton, Brighton
Manchester, Birmingham, Leeds
Our reports are consistently accepted by all UK planning authorities.

 
BRE & CIBSE Requirements
Our calculations follow official standards, including:

BRE Water Efficiency Calculator for New Dwellings (WECND)
Required by Building Regulations
Used for demonstrating 110/105 L/person/day compliance
Recognised by building control and warranty providers (NHBC, LABC, Premier Guarantee)
CIBSE Guidance (Complementary)
While CIBSE does not publish its own calculator, CIBSE building services guidance reinforces:

Efficient water system design
Flow rate and pressure management
Sustainable water strategies
We align with both BRE methodology and CIBSE recommended practices.

 
What Our Part G Water Efficiency Report Includes
Our comprehensive report contains:

✔ BRE Water Calculator spreadsheet (official format)
✔ Full water consumption calculations
✔ Fittings and flow-rate summary table
✔ Compliance statement with 110L/105L target
✔ Recommendations to achieve compliance if initial design fails
✔ Council-ready PDF report for planning/building control

Where required, we can also:
✔ Recommend compliant taps, showers, and toilets
✔ Provide alternative specifications to meet stricter council limits

 
Why Choose Us?
Fast turnaround (same day available)
Reports accepted by all UK councils
Fully compliant with Part G, BRE standards, and CIBSE guidance
Clear, simple, planning-friendly documentation
Affordable option for single dwellings or large developments
Expert support throughout your submission
 
What We Need to Start
To complete your Water Efficiency Calculation, simply send:

Floor plans (optional but helpful)
Specification of:

Taps (flow rates)
Shower heads
Bath size
WC flush volumes
Dishwasher/washing machine (efficiency)
Or we can estimate based on typical fittings if you don’t have details yet
We handle the rest.

 
Get Your Part G Water Efficiency Calculation Today
Need a fast, compliant Water Efficiency Report for planning or building control?

Contact us today for a quote or send your fitting details to begin.

Water Efficiency Calculations – Part G Compliance
BRE Water Efficiency Calculator – Part G Report
Part G Water Efficiency Report for New Dwellings
Part G Compliance – Water Efficiency Assessment
 
Part G Water Efficiency Calculations for new homes. BRE-compliant reports for councils and building control. Flow rates, fittings, and water targets included.

Fast Part G water efficiency calculations using BRE methodology. Council-approved reports for planning and building regulations.
Professional Part G water efficiency reports. Compliant with BRE and CIBSE guidance, including taps, showers, WCs, and appliances.
Part G Water Efficiency Calculator reports for developers and architects. Shows compliance with 110/105 L/person/day targets for councils.