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Indoor Water Use

Wat 1: Indoor water use

Credits Available: 5 (mandatory elements)

Credits are awarded for reducing the consumption of potable water within the home. Assessment is based on the predicted average household water consumption for the type of dwelling and takes into account the efficiency of internal fittings (e.g. toilets, dishwashers). Within the Code, key targets for water usage are defined at each code level. A dwelling can only qualify for a higher code level if water consumption mandatory levels have first been met. The maximum water consumption required for different Code levels, and available credits, are outlined in the table below.

Indoor Water Use Criteria Table

Table taken from the Code for Sustainable Homes Technical Guide (May 2009, Version 2) pg 98.

The water consumption calculation is undertaken using the Code Water Calculator, available from BRE Global Ltd. The calculator assesses each water consuming installation within the home. An example water calculation spreadsheet can be viewed on the BREEAM Extranet here (pdf, username:public, password:public). Useful background information relating to the calculation methodology and its use is contained within the Government guide - 'The water efficiency calculator for new dwellings' (pdf). The Code aims to reduce water consumption and promote water re-use, as the Environment Agency has identified over 50% of potable water in the UK is used to flush toilets and for washing. The processes of water purification, abstraction and supply have high energy requirements. Advantages of reducing water usage within the home include reduced utility bills and reduced discharge of spent water into the drainage network, which reduces the risk of flooding. Under the Code, potable water extracted via a private borehole is regarded as mains water and dwellings utilising a borehole water supply must still be assessed for water consumption.

Reducing the amount of potable water used within dwellings can be achieved by scrutinising the amount of water consumed by each water utilising installation and ensuring they represent the most efficient installations on the market. To reduce potable water consumption levels further consideration could be given to using rainwater recycling systems or a greywater recycling systems to provide non potable water for toilet flushing or washing machines. A number of water efficient products have been developed to reduce water consumption within the domestic environment.

Evidence Required

Code Assessors will require drawings of installations, along with evidence that steps have been taken to avoid microbial contamination of the hot and cold water system, in order to award credits. Manufacturer specifications should also be provided to back up water efficiency claims for the installations. For full code assessor requirements reference should be made to the Code for Sustainable Homes - Technical Guide (May 2009, version 2) (pdf).

Additional Information

There are a number of schemes recognising water efficient products however no single unified government scheme exists.

BRE Global Ltd

BRE Global Ltd run accreditation schemes for water efficient baths and water terminals, and low flush toilets. Manufacturer's products are tested and their water efficiency credentials verified. Low flush toilets are required to be Class 2 products as listed by the Water Regulations Advisory Scheme (WRAS) and conform to BS EN 997:2003, with a single flush at or below 6 litres water volume. Baths and bath type installations must conform to the relevant British Standard (BS EN 14516:2006 for conventional baths, BS EN 12764: 2004 +A1:2008 and EN 60335-2-60 for whirlpool baths) and have fill volumes less than those generally in current use, in order to be certified under the scheme. Water efficient terminals can include flow restrictor and aerator devices for fitting to taps and showers. Shower packages (comprising a device to supply water at around 37 degrees, a showerhead and associated pipe work) are also covered by the scheme. Products are tested at 3 bar pressure to determine flow rate and any variation in flow rate with pressure change. Aerated shower products are required not to significantly vary output water temperature from the input water temperature. Certification is given to terminal fittings which utilise lower flow rates than those generally on the market.

All three schemes certify products suitable for use under the Code for Sustainable Homes. More information can be found on the BRE Global website.

Bathroom Manufacturers' Association's Water Efficiency Labelling Scheme

This is a non-governmental certification scheme established and run by the Bathroom Manufacturers Association (BMA). The scheme identifies water efficient products that use less water compared to others on the market. The scheme was introduced to reduce water consumption and drive innovation in the design of bathroom products. Certified products are labelled with the 'Water Efficient Product Recommended' label and display a scaled water efficiency rating showing average water usage volumes for the product. The labels offer a means of instant comparison. Further details regarding the scheme and water saving advice can be found at the Water Efficient Product Labelling website.

Water Efficiency Label Water Efficiency Rating

Waterwise Mark

Waterwise is a non profit body operating in England, which receives funding from the water industry and consultancy work it undertakes. Each year the body awards the Waterwise Mark to water consuming products with high water efficiency credentials and those that reduce water wastage. The scheme has been running since October 2006. Product categories awarded the mark include toilets, urinals, water butts, flow restrictors and shower heads, amongst others. A full list of products with the Waterwise Mark and further information can be found on the Waterwise website.

Waterwise Mark

ECA Water Technology List

The Government's Enhanced Capital Allowance Scheme encourages businesses to purchase water technologies that promote sustainable water use. The scheme allows businesses to write off the cost of investments in sustainable water technologies by allowing them to cover the investment cost using taxable profits from the period in which they make the investment. A list of products recognised under the scheme and further details of the application process can be viewed at the ECA Water Technology website.

Rainwater Recycling Systems

These systems are designed to collect rainwater run-off from hard standing and features such as roofs. The water is then distributed to points of use within the house via a network of pipes, where it can be used in place of potable mains water in toilet cisterns for toilet flushing or within washing machines.

Rainwater Harvesting System Diagram

Diagrammatic representation of a rainwater harvesting system courtesy of

Greywater Recycling Systems

These are systems for the collection of used potable water from installations such as baths, showers and taps. Once collected, the used water is filtered and treated then redistributed to water consuming installations, such as toilet cisterns and washing machines, which do not require potable quality water for their operation.

Grey Water Collection System Diagram

Diagrammatic representation of a greywater collection system courtesy of

Product Focus

Products currently available include: