From water fittings to your Part G result in minutes.
Our online Part G water efficiency calculator guides you through the information required for your dwelling, completes the calculation and gives you an instant PASS or FAIL result.
It's free to calculate. If you need professional calculation documents afterwards, you can generate them directly from your completed result.
Simple from start to finish
Everything is guided as you go
You don't need to understand the Part G calculation methodology beforehand. The calculator asks for the information it needs and handles the calculation for you.
Choose your project
Start with a single dwelling or a multi-plot residential development and enter the basic project details.
Enter the specification
Add the proposed toilets, taps, showers, baths and appliances. Use standard assumptions or enter the exact product specifications available for the project.
See whether it passes
The completed calculation shows the dwelling's water consumption in litres per person per day and compares it against your selected target.
You probably already have everything required.
For a detailed Part G water efficiency calculation, you'll generally need the proposed quantities and performance of the main water-using fittings within the dwelling.
If you don't have every manufacturer's specification available yet, the Quick Calculator can use standard assumptions to help assess the proposed design.
Open the Calculator →Toilets Flush volumes
Wash-hand basins Tap flow rates
Kitchen & utility sinks Tap flow rates
Showers Flow rates
Baths Bath capacity
Appliances Water consumption
Choose the level of detail that suits your project
Both routes use the same calculation system. The difference is simply how much specification information you want to enter.
Quick Calculation
Best when you want a fast assessment or don't yet have every manufacturer's specification available.
- Enter fixture quantities
- Uses standard specification assumptions
- Fastest route to a result
- Ideal for early-stage checks
Advanced Calculation
Best when product specifications are available and you want the calculation to reflect the proposed fittings accurately.
- Enter actual WC flush volumes
- Enter tap and shower flow rates
- Enter bath and appliance capacities
- Ideal for final project specifications
See the answer before you spend anything.
Completing the calculator and viewing your PASS or FAIL result is completely free.
If the dwelling fails, amend the proposed specification and recalculate as many times as necessary. There's nothing to purchase until you're happy with the result.
Professional calculation documents
Water Efficiency Report Project-specific calculation result and supporting details.
Part G Calculation Schedule Detailed breakdown of the calculation and specification.
Ready to check your property?
Start your Part G water efficiency calculation now and see your PASS or FAIL result before spending anything.
Start Your Free Calculation No account or payment required to start