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Water Calculations

Water Calculations For New Builds (Part G)


Airtight Testing Staffordshire provides water calculations for new builds with a fast turnaround. We provide water calculation testing for new builds across the UK. Our aim is to make complying with Part G building regulations easier than ever before.

We make it simple to get water calculations for new builds. If you provide us with the information, we will do the water calculations for you. With our expert advice, you can move quickly and seamlessly through the regulation process.

This takes away the stress of making your building compliant and allows you to focus your energy on your new build project. Click here for a water calculation checklist.


It is important to remember that you have the responsibility to ensure that your new build property is compliant. Part G regulations state that new build properties must use 125 litres of water per person per day. In some cases, this can be 105 litres depending on the local authority.

Part G deals with sanitation, hot water safety and water efficiency requirements, so it is important that your property is compliant. If not, you could be served with an enforcement notice. This regulation seeks to ensure that your new build property has a safe water supply and is not wasting water. It also requires you to keep a record of any appliances using the water supply to ensure they are efficient and includes many more regulations you must follow.

To ensure you are compliant with Part G regulations we can complete the water calculations for you and help ensure that building control is provided with the correct water efficiency calculations, to save you time and money.


Your water calculations should be done as soon as you are able to follow the three rules below:

  • You know which products are going to be used
  • Before you’ve purchased any products
  • When you have a clear idea of the number of fittings

Following these 3 rules means you can get a more accurate water calculation. Plus, it allows for flexibility if any alterations need to be made.

You shouldn’t make any purchases of products before doing the calculation. If they don’t comply, they may need replacing and this could cause you to incur more charges.


To help you with your water calculations, we need some information from you. This allows us to provide an accurate water calculation to building control and save you any hassle. The table below details everything we need from you:

Information Needed


The calculation involves internal ‘potable’ water and accounts for the number and type of the following products:

  • Toilets
  • Taps
  • Baths
  • Showers
  • Washing Machines
  • Dishwashers
  • Rainwater Recycling
  • Water Softener
  • Grey Water Recycling
  • Waste Water Disposal

Once we have this information we can begin with the water calculations. The water calculations are bespoke to you and your building. If it is compliant with Part G building regulations, we provide a report providing all the relevant information to you and building control.

However, if you need further work or products we can suggest solutions for you which are efficient and cost-effective. We will guide you through the process you need to go through for your water calculations to be compliant.


Airtight testing Staffordshire is here to help you through this often confusing regulation process quickly and easily. We have expert consultants who can complete accurate water calculations. They can also offer you expert advice on how to achieve compliance with Part G regulations, should you need it.

Airtight testing Staffordshire offers a range of services to help your new build pass building regulations easier than ever before!