Water Efficiency Calculations in UK

Water Efficiency Calculations

Part G of the Building Regulations in the UK covers water efficiency requirements for new buildings. The goal of these regulations is to ensure the sustainable use of water in domestic and non-domestic buildings.

Key Aspects of Water Efficiency

1. Water Consumption Targets:
   • The regulations set a maximum allowable water consumption for new homes, which is currently 125 liters per person per day. This target includes water used for drinking, cooking, washing, and sanitary purposes.
2. Fittings and Appliances:
   • To meet the water consumption target, builders and developers need to install water-efficient fixtures and fittings. This includes:
     • Dual flush toilets
     • Low flow taps and showers
     • Water-efficient washing machines and dishwashers
3. Calculation Method:
   • The water consumption calculation is typically carried out using a water efficiency calculator approved by the government. This calculator takes into account:
     • Flow rates of taps and showers
     • Volume of water used per flush in toilets
     • Water consumption of appliances like washing machines and dishwashers
4. Rainwater Harvesting and Greywater Recycling:
   • To further reduce mains water consumption, systems for rainwater harvesting and greywater recycling can be installed. These systems collect and reuse water for non-potable uses such as flushing toilets and garden irrigation.
5. Compliance:
   • Builders must demonstrate compliance with Part G by providing calculations and evidence that the water consumption of the new building meets the required standards. This may involve submitting documentation to building control bodies as part of the building approval process.
6. Certification:
   • Compliance can also be certified through schemes like the Code for Sustainable Homes (for residential buildings), although this specific code has been replaced by other standards and guidelines in many regions.