Combe Martin is a small coastal resort on the north Devon coast. Two water courses enter the 110-metre-wide sandy bay, the Furze Park Stream and the River Umber which drains directly from the northern slopes of Exmoor. Rainwater from the steep slopes in the area often floods the river, overcoming the sewerage network.
The purpose of this pilot project was to help the bay achieve ‘good’ bathing water status, by reducing the frequency with which CSOs discharge untreated stormwater into the bay.
Multiple improvements to the serving CSOs over the past 25 years have so far failed to rectify the discharge of polluted water into the bay. Due to insufficient water quality standards, as monitored by the Environment Agency under the Bathing Water Directive, bathing at Combe Martin has been classed as poor from 2017 to 2020, with 62 pollution risk warnings issued in 2020 alone.
WHAT WE DID
With the assistance of South West Water’s engineering consultants, Stantec, 34 homes were equipped with a domestic version of the SDS Intellistorm® rainwater recycling and attenuation system. This comprised of a slim, space-saving 275 litre capacity rainwater storage tank, connected to the main downpipe from the roof and fitted with a solar-powered, computer controlled box.
Together, the tanks have a combined storage capacity of over 9,500 litres. Unused rainwater is released automatically, but only when there is no pressure on the network. Data received via SDS SYMBiotIC™ over the first six months of the project indicate that a single ‘smart’ water tank stores as much water as 7 traditional water butts and is on course to attenuate more than 3,500 litres per year.
Results show the benefits SDS SYMBiotIC™-enabled rainwater management systems can deliver, realising total stormwater attenuation volumes 19 times greater than the volume of the tanks installed. In addition, residents save money on reduced water bills by recycling rainwater.
This level of performance could not be realised in distributed, plot-scale systems without dynamic management. Data from the trial shows that without smart intervention, many systems, where water is not reused, would have filled once and remained full.
The project has contributed to improved water quality within the River Umber and the Combe Martin bathing water. In 2021 the bathing water achieved ‘Sufficient’ status for the first time since 2016, preventing the automatic de-designation of the bathing water by interrupting five consecutive years of being classified as ‘Poor’.