Part G Water Calculations:

Part G Water Calculations

Since April 2010 all new build residential development and residential development arising from a change of use must comply with Part G of the Building Regulations and achieve a water consumption rate of no more than 125 litres per person per day.

How is a Part G calculation carried out?
The Part G calculator has been devised by the Department of Communities and Local Government and takes a standardised approach of typical occupant behaviour – for example how many times the average person uses the toilet or how long the average person stands under the shower. These usage factors are then applied to the specific capacities and flow rates of the following water consuming appliances:- 

  •  Toilets
  •  Showers
  •  Baths
  •  Taps
  •  Washing Machines
  • Dishwashers


What information do I need to provide?
To carry out a water calculation we need information on the flow rates, measured in litres per minute, and the capacities of your sanitary ware. However it is not uncommon that at the early design stage this level of information is unavailable. Don’t worry! We can help. We can provide guidance on the sanitary ware to install or the level of flow restriction to be achieved – just pass this information to your plumber and you will ensure compliance with the Regulations