p and down the country, weather patterns are being disrupted by climate change, putting increasing stress on the UK’s water supplies. 2017/18 has been a case in point – we’ve experienced a particularly harsh winter with high levels of rain and snowfall causing floods, followed by the driest, hottest summer in decades, resulting in water levels falling to a record low. In fact, a recent report from the Environment Agency shows that England will face serious shortages by 2050 if rapid measures aren’t put in place to curb water use and wastage.
With extreme weather events, such as droughts and flash floods, becoming more and more commonplace, it is vital that architects and constructors can ensure their projects are not putting extra strain on our water supplies – whilst adequately protecting against the risk of flooding. In short, this means turning to (and specifying) effective water management solutions right from the get-go.
It’s no wonder, therefore, that rainwater harvesting (RWH) is rapidly gaining popularity among specifiers as the single most effective way to ensure a reliable, uninterrupted supply of water – all whilst delivering a sustainable solution that helps meet stringent BREEAM criteria. In fact, it was only a few months ago (July 2018) that OFWAT urged Brits to take up RWH, stressing that climate change and a growing population are threatening our water supplies.
But, how exactly can specifiers play their part to save water and provide effective flood defences at the same time? The answer is a combined water management solution. This is where RWH tanks are bolstered with stormwater management (SWM) capabilities to create a system that not only complies with strict council water run-off requirements but also protects end-users against the risk of flooding.
However, when it comes to successfully specifying the right water management solution for your projects, it ultimately boils down to having a good knowledge of what’s available on the market.
Rainwater harvesting: don’t let the rain drain away
In the UK, each person uses on average 148 litres of water every day. Most of this water is used for toilet flushing, cleaning processes, irrigation, car washing or air conditioning – so it does not need to be of drinking quality. With this in mind, it’s easy to understand why we are currently experiencing a rapid rise in the uptake of RWH as a way to minimise our dependence on increasingly costly water from the mains. When correctly specified and installed, an efficient RWH tank can make a huge difference on end-users’ bills. It reduces mains water usage by between 40 and 50%, and with additional tax incentives available to encourage investment in water-saving technologies, the financial case is clear to see.
Installing an RWH solution not only cuts costs substantially, but it also saves a vast amount of valuable water and has a hugely positive impact on the environment, too. It is also particularly attractive for architects and constructors working on new-build projects who are looking to meet BREEAM criteria (which assess a building’s environmental, social and economic sustainability performance). To achieve the sought-after ‘Excellent’ rating, new premises must adhere to strict energy consumption, sustainability and water-saving standards – and with up to three BREEAM credits available for RWH, fitting a system can be the decisive factor in reaching the highest possible accolade.
Stormwater management: protecting against future floods
Whilst collecting excess rainwater and retaining it for reuse provides an extra layer of security against flooding, it can’t replace an entire sustainable urban drainage system (SuDS). This is why an efficient, bespoke stormwater solution is crucial to ensure long-term protection against flooding. Not only this – the management of excess stormwater is required by local environment authorities (who set strict water run-off requirements) and stipulated in guidelines set out by the Flood and Water Management Act of 2010.
The good news is, manufacturers have been quick to rise to the challenge in the form of new product developments. Modular, underground stormwater tanks available on the market today can be combined with RWH in a one-tank solution to provide a cost-effective two-in-one system. This is done by adding a crate-style soakaway or a tunnel system (sized according to the infiltration rate of the soil).
Tucked away neatly out of sight beneath the ground, these ‘cells’ can be installed virtually anywhere. What’s more, the most modern tanks (such as GRAF UK’s EcoBloc range) are fully inspectable; they feature inlet shafts and in-built inspection channels for optimum performance and complete peace of mind for the lifetime of the tank. Whilst systems have traditionally been designed with a 30-year storm in mind (the kind of weather event that is statistically likely to happen just once in a 30-year period), we have seen a shift in standard practice as the threat of climate change has heightened over the past five to 10 years. This means that most systems are now designed with enough capacity to handle a 100-year storm, with an additional 20% contingency buffer for climate change on top of this.
A two-in-one solution fit for the future
When it comes to complying with ever-tightening flood defence regulations and saving what is perhaps the planet’s most valuable resource – water – the building sector is increasingly turning to specifiers for guidance. Those who are actively implementing effective water management solutions, and incorporating RWH and SWM to future-proof their projects, are well placed to deliver the very best long-term financial and environmental benefits.
