This was a lively session with 21 people in attendance.
Peter Fane (SCDC councillor, and 2G3S co-chair) introduced the speakers, and started the session by noting that a new development corporation – the Cambridge Growth Company -will shortly come into existence with an ambitious agenda for growth and development in Cambridge and the surrounding area between now and 2050, with goals for increases in residential accommodation as well as business developments. Any such developments will inevitably increase pressure on water resources, making the issue of how we manage them even more important.
An example of how the water issue is being treated in current planning policy is Darwin Green, a proposed development for which planning permission was originally denied due to objections by the Environment Agency that there was not enough water available. In order to overcome this objection, the government advised that water credits and future developments in water availability should be taken into account, along with the expected date of occupancy of the new homes, resulting in the development being given the go ahead, despite the concerns of local councillors that the new reservoir was unlikely to be in place in time and that the effectiveness of water credits is unproven.
The first of the two invited speakers was Vicky Thatcher, head of Water Strategy and Environment at Cambridge Water. Cambridge Water, as the provider of our drinking water, is regulated by OFWAT, the Environment Agency (EA), and the Drinking Water Inspectorate. Cambridge Water is granted a licence (“derogation”) to abstract a certain quantity of water from the chalk acquifer per year. This amount is reviewed every 5 years, and the company would be liable to a fine if this limit were exceeded. The plan for the next 25 years sees a growing gap between available supply and demand. This is due to growing demand and also an expected reduction in the quantity of water that Cambridge Water is licenced to abstract in future. The EA require this amount to reduce due to climate change and other factors so that the level of damage to the environment caused by abstraction does not grow worse.
About 1/3 of this gap is to be addressed by reduced demand per customer, with the remaining 2/3 covered by two additional sources: The Fenland Reservoir (scheduled for completion in 2037 but many people expect that the project will overrun) and a pipeline bringing water from Graffham Water, currently planned to go onstream in 2032.
Customers of Cambridge Water consume on average 119 litres/day per person. This is too high to be sustainable with the current population. This is the lowest average consumption in the UK (the countrywide average is about 140 litres/person/day). The Cambridge area has a relatively high proportion of properties having water meters: over 80%. Cambridge water is intending to raise this proportion to close to 100% over the next 5-10 years. Water metering could become “smarter” in future, but “smart” water meters are not like smart gas and electricity meters – there would be no in-home display showing actual and cumulative consumption. There was some discussion about how numbers like a 5 million litres a day excess consumption could best be visualised and communicated.
Several members of the audience noted that they consume only about 70 litres/person/day – Vicky claimed her own usage was similar. Cambridge Water aim to achieve the reduction in average consumption by a combination of public information to change behaviour, making clear what’s normal and what is required (peer pressure etc), and by identifying anomalously high water readings (or sudden changes) that indicate a leak, and taking action to eliminate it. This includes informing and visiting properties to identify the cause. “Leaking loos”, where a constant stream of water runs from the cistern into the toilet bowl, are a common cause of high consumption and can be undetected by the occupant if not looked for.
The second speaker was Yair Perry of Water Sensitive Cambridge, who design and install rain gardens and other ways of rainwater harvesting, to reduce risk of flooding and where possible prevent pollution of waterways from excessive run off from hard surfaces. Their slogan is “Lets keep more rain out of the drain”.
Yair described how WSC had successfully mitigated road flooding in Chesterton by installing a roadside rain garden, and talked about their programme of installations in schools, notably the Icknield Primary School in Sawston, where pupils can learn about the issues and participate in the planting of the rain gardens.
Their “Slow Flow” planters, possibly combined with a water butt, are designed for capturing water from downpipes in residential and other buildings, absorbing rain that would otherwise run off during heavy showers (where a water butt alone would not prevent this once full).