Part G Water Calculations
Complete your Part G water efficiency calculation online and check whether your dwelling meets the required daily water consumption target.
Enter your proposed sanitary fittings and appliances, check against the applicable 110 or 125 litre target, and generate a professional Building Control report when you're ready.
What is a Part G
Water Calculation?
A Part G water calculation demonstrates that a new dwelling meets the water efficiency requirements of the Building Regulations.
The calculation uses the specification of the water-using fixtures and appliances within the property to estimate daily water consumption, expressed in litres per person per day.
Your Specification
Showers, taps, baths, WCs and water-using appliances.
Water Consumption
Daily consumption is calculated in litres per person.
Part G Target Check
Your calculated result is checked against the required target.
per person / day
per person / day
When Are Part G Water Calculations Required?
Water efficiency requirements apply to new dwellings under Part G of the Building Regulations in England. The requirements for conversions depend on the nature of the proposed works.
New Build Homes
New residential dwellings must demonstrate compliance with the applicable water efficiency requirement. Calculations assess the proposed fittings and appliances before completion.
Conversions
Certain conversions and material changes of use may involve Part G requirements. The exact obligations depend on the project and should be confirmed with Building Control.
Building Control
Where a water efficiency calculation is required, Building Control may request evidence showing that the proposed specification meets the relevant consumption target.
Understanding the 125L and 110L Water Efficiency Targets
Part G of the Building Regulations sets water efficiency requirements for new dwellings in England. The applicable target determines the maximum calculated daily water consumption.
Standard Water Efficiency Target
The standard Part G requirement for new dwellings in England is a calculated water consumption of no more than 125 litres per person per day.
Higher Water Efficiency Standard
An optional requirement of 110 litres per person per day may apply where it has been imposed through the relevant planning and regulatory process.
How Your Result Is Assessed
In this illustrative example, the dwelling's calculated consumption is 107.6 litres per person per day. This is below the 110 litre target and therefore also meets the standard 125 litre target.
What Information Do You Need for a Part G Water Calculation?
Getting started is easier than you might think. Our online water calculator offers two ways to complete your calculation, depending on how much information you have available.
If you are still planning your development, the Simple Calculator lets you get started using basic property details such as the number of bedrooms, toilets, showers and baths.
Already know your proposed sanitaryware? Switch to the Advanced Calculator to enter individual flow rates, flush volumes and appliance specifications.
You can start with the simple option and explore your water efficiency result before finalising your fittings. For a final Building Control submission, ensure the calculation reflects the actual proposed specification.
Simple or Advanced?
Just Know Your Property
Perfect for getting started without detailed product specifications.
Enter Your Exact Specifications
Ideal when your sanitaryware and appliance specifications are available.
How Does a Part G Water Calculation Work?
From entering your property details to obtaining a professional water efficiency report, our online calculator makes the process straightforward.
Enter Your Property Details
Choose Simple or Advanced mode. Start with basic property information or enter your detailed sanitaryware specifications.
Calculate Water Consumption
The calculator estimates daily water usage and compares your result against the selected 110 or 125 litre target.
View Your Result for Free
See whether your calculation passes or fails. Review your inputs and make changes where necessary before proceeding.
Get Your Building Control Report
When you're satisfied with your calculation, purchase your PDF report to support your Building Control submission.
Get Your Part G Water Calculation Report
Check your water efficiency calculation online for free, then purchase a professional PDF calculation report when you're ready to submit your information to Building Control.
Part G Calculation Report
Professional PDF documentation
Once your calculation is complete, you can generate a report containing the information needed to support your Building Control submission.
- Project and dwelling information
- Water-using fixture specifications
- Calculated daily water consumption
- Applicable 110L or 125L target
- Calculation results and supporting schedule
Calculate for Free.
Pay Only for Your Report.
Get started without paying upfront. Review your water efficiency result before deciding whether to purchase your PDF report.
Professional Part G calculation report