Water Efficiency Calculator

Part G Building Regulations & Optional Requirement Compliance

Part G Compliant 125 L/p/d Standard

110 L/p/d Target Optional Requirement

BREEAM Ready 100 L/p/d Excellent

Development Details

Development Type

Number of Dwellings

Average Occupancy (persons)

Water Stress Area

Compliance Target

Fittings Specification

WC Flush Volume (litres)

Single flush volume (default 6L)

Basin Tap Flow Rate (L/min)

Bath Capacity (litres)

Shower Flow Rate (L/min)

Kitchen Sink Flow Rate (L/min)

Washing Machine (L/cycle)

Dishwasher (L/cycle)

Water Saving Features

Dual flush WC (4/6L)

Low flow taps

Aerated shower head

Flow restrictors fitted

Grey water recycling

Rainwater harvesting

Water meter installed

Leak detection system

Water Usage Assessment

litres per person per day

PASS

Usage by Fitting Type

Basin Taps

Bath

Shower

Kitchen Sink

Washing Machine

Dishwasher

External Use

Development Totals

Annual Water Consumption

0 m³

Annual Cost Savings

£0

Effective Features Applied

About this tool: Water Efficiency

Part G Building Regulations water efficiency — fittings specification, litres per person per day calculation, Optional Requirement (110 l/p/d), and BREEAM water credits.

When to use it

Use when your LPA has adopted the Optional Requirement for water efficiency (110 l/p/d instead of 125 l/p/d). Check your local plan.

Policy and guidance it draws on

Building Regs Part G, Local Plan water policies

Part of Environmental Intelligence

Use these tools when preparing technical reports and compliance documentation. Many of these are validation requirements — submit without them and your application will be returned. Use the Validation Pre-Flight tool to check which ones you actually need.

Guidance to help you prepare — not formal planning advice. Check the current policy text and your council's local plan before relying on it.