Planning for sustainable water management
Water management plans can help to reduce water use, for example by introducing high water efficiency standards for new and refurbished buildings.
Planning for water resources at city scale will be heavily informed by national and regional work. For example, urban capacity studies at the city scale should be informed by regional water resource strategies to ensure water supply demand from projected growth can be met sustainably and locally. Unlike carbon it matters where water is saved (or recycled) as the effects are felt locally rather than globally. Generally, we should be seeking to avoid the need for water transfers over long distances.
The principle of ‘water neutrality’, which suggests that following new development potable water use should be equal or less than pre-development levels, is one option being considered to inform the accommodation of growth and the design of new developments.
Research led by the Environment Agency, explored ‘the feasibility of achieving water neutrality at the sub-regional scale in the Thames Gateway where total water use after new development is equal to or less than total water use before the development’. It explored various combinations of options to achieve water neutrality encompassing:
- making new developments much more potable water-efficient
- ‘offsetting’ new demand by retrofitting existing homes and other buildings with more efficient devices and appliances
- expanding metering and introducing innovative tariffs for potable water use to encourage households to use water more efficiently.
A series of scenarios were developed and the proportion of savings attributable to new homes, existing homes, non-households, compulsory metering and variable tariffs were calculated and varied by scenario.
The introduction of compulsory metering (in existing properties) was included in the scenarios. Metering accounted for around 10 per cent of all water saved in each scenario reaching neutrality. It was concluded that paying for the water used provided an important financial incentive to households and was the measure that had the greatest acceptance by residents in the gateway who were surveyed as part of the study.
Building new homes to higher water efficiency standards provided between 9 and 17 per cent of the total water saved. The additional cost of fitting water meters and water efficient appliances and devices for new homes was calculated to be within the range of £275 to £765, averaged across all homes built in the gateway between 2005 and 2016.
Retrofitting existing homes with simple ‘fix and forget’ measures such as variable flush toilets devices and low-flow showerheads and taps was found to save between 23 to 47 per cent of the total water saved. The cost for existing homes (to pay for retrofitting, fitting a meter and applying tariffs where applicable) was £135 to £154 per house, with costs averaged across all existing households in the gateway in 2005-06. The costs of moving towards and potentially achieving neutrality were therefore concluded to be competitive with those of other options, such as leakage management.
As only 30 per cent of homes existing in 2050 will have been built after 2006, it is important to explore improvements in the way existing buildings use water, as well as building highly efficient new stock. In the south east of England, the Three Regions Climate Change Group has issued a guidance document for policy makers that includes three case studies: a 1930s house, a 1960s flat and a block of flats.
The report also found that the greatest gains could potentially be found from improving the water efficiency of non-domestic buildings. It recommended that local authorities could play a key role both in raising awareness on the benefits of water savings for businesses and in incorporating water efficiency criteria into their procurement procedures for new and public buildings.
CABE and Urban Practitioners
with the cities of Birmingham, Bristol, Leeds, Liverpool, Manchester, Newcastle, Nottingham and Sheffield