Part G Water Calculator — Water Efficiency Assessment
Calculate whole-dwelling water consumption per person per day using the fittings approach, in accordance with Approved Document G for England.
What This Calculator Does
This tool helps architects, designers, and building professionals assess whether a new dwelling meets the water efficiency requirements of Approved Document G. It calculates total water consumption in litres per person per day (l/p/d) using the fittings approach.
Compliance Targets
- 125 l/p/d — Standard requirement for all new dwellings
- 110 l/p/d — Optional requirement set by some local planning authorities
Fittings Assessed
- Basin taps (excluding kitchen) — flow rate at 3 bar dynamic pressure
- Showers — flow rate at 3 bar dynamic pressure at 37°C
- Baths — capacity to overflow in litres
- WCs (toilets) — full flush and part flush volumes for dual flush
- Kitchen and utility taps — flow rate at 3 bar dynamic pressure
- Washing machines — litres per kg dry load
- Dishwashers — litres per place setting
- Waste disposal units and water softeners
How It Works
Enter the specifications for each fitting in the dwelling. The calculator uses use factors from Approved Document G Table 2.2, applies a normalisation factor of 0.91, and adds a 5 l/p/d external water use allowance to determine total consumption.
Pricing
£24 + VAT per dwelling. No fee if the assessment fails to meet compliance. Professional A4 reports with full calculation breakdown for Building Control.
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