What is a Water Neutral Development?
A Water Neutral development will not add to the overall existing water demand of an area or
catchment and will have zero impact on existing water abstraction requirements or water mains supply.
Fresh Water Is A Finite Resource?
Fresh water resources are finite but there is an ever increasing demand on them owing to rapidly growing populations, urbanisation, economic activities and the requirement to sustain ecological flows and wildlife.
In many regions of the world this has led to over abstraction of groundwater resources and from rivers, eutrophication of rivers, water scarcity and inequitable distribution of water. Significant structural failure, overwhelmed infrastructure, poor policy and governance has made the perilous situation worse. Climate Change has exerbated the issue resulting in extreme droughts like those experienced globally in 2022 and flooding in other regions.
UK's Dwindling Ecological Flows & Drying Wetlands
In Southern England the Sussex North Water Resources Supply Zone has dwindling ecological flows, resulting in the drying of wetlands which has caused the nature regulator, Natural England to enact a new Habitat Regulations Assessment (HRA) directive. This requires that new water use for residential and commercial developments must be water neutral. This measure has been stipulated in order to protect ecological flows and reduce the demand for increased groundwater abstraction from the local public water supply wells at Hardham. As this could adversely impact the integrity of the Arun Valley which is a critical habitat for many important species, and source of drinking water.
The aim of this locally instituted water neutrality policy is to minimise the impact on existing water resources, infrastructure, and the environment. Consequently for every new development, water demand should first be minimised with any remaining water demand offset, so that the total demand on the public water supply (mains, treated or abstracted) in this catchment / region is the same after development as it was before the development was built. Thus for all new developments there would be a requirement to offset water use from existing residential/school/building premises within the same water resource zone to create the water resources required to service the new development.
Water Neutrality can be achieved by reducing water use, reusing and recycling water onsite and finally by offsetting the remaining water demand in the same water supply zone or aquifer catchment area.
Following this hierarchy results in the biggest water savings in the most cost effective manner. Water efficient fittings, smart metering, total washroom control and instilling a water saving culture will result in significant water savings at minimum cost. Any residual water demand for the new development is then offset by water efficiency improvements on existing properties registered on theWaterBank.
STEP 1 - REDUCE WATER USE
Water Saving Culture
STEP 2 - WATER REUSE
STEP 3 - OFFSET WATER
As much as over exploitation of water occurs in the natural environment causing adverse impact, this is also true in social and economic settings. Water equity can be achieved by halting over abstractions of finite water resources and implementing policies and tariffs that require high water users and new water demands to offset their proposed water uses. For the UK Market we have developed theWaterBank, to facilitate the generation and trade of water offsetting opportunities to reduce the demand of water resources and thus create water resilient communities and environments.
theWaterBank is a database that matches developers with existing property owners willing to offer their existing buildings for retrofits to achieve significant water reductions. More importantly these savings will need to be made within the same water resource zone inc which the development is proposed. Offsetting is usually done by working in partnership with local organisations, housing associations, the council, businesses, churches and charities.
Typical Options for water offsetting schemes are as follows:
All offset schemes will require a water efficiency audit and a detailed water efficiency retrofit design.
The developer would then need to donate/pay a fee to a housing association to retrofit their homes or existing businesses.
Offsetting by fixing leaks over and above planned work by water companies.
Retrofitting school buildings or local hotels to improve water efficiency.
Retrofitting water reuse schemes such as in public buildings or schools or private institutions like hotels in the area.
Installing smart meters (above what was already planned by water companies) can also help encourage water saving behaviours, and provide information on how much water is being used.
In addition to the above water offsetting activities councils may require an investment into awareness campaigns and promoting water saving behaviours via S106 Obligations.
Implications for Developments
On brownfield developments it is possible in most instances to use water efficient fittings to match historic use. The criteria for water neutrality typically allows the developer to consider historic water consumption between 10 to 20 years prior to the development. Brownfield sites could be golf courses, workshops, offices or even old houses being converted. In some instances a water reuse strategy will need to be adopted, which may include rainwater harvesting or greywater recycling or a combination of both.
Greenfield Developments & Strategic Sites
Greenfield and strategic development sites are significantly more difficult to achieve Water Neutrality and will require a much more detailed analysis and intervention. Typically this would include establishing significant water demand associated with the site which could be the irrigation of historic farm fields or water use associated with other historic uses of the farm such as livestock. On Greenfield developments a minimum of Steps 1 and 2 of the Water Neutrality Hierarchy, which means that rainwater harvesting and greywater recycling will need to be implemented.
Greywater recycling will result in a reduction of domestic demand by approximately 45%. However in most instances it is anticipated that for some greenfield developments and strategic developments will also require to offset water.