Mobilising Citizens for Adaptation: building local flood resilience through cooperative rainwater harvesting (MOCA)

Mobilising Citizens for Adaptation: building local flood resilience through cooperative rainwater harvesting (MOCA) explores whether and how rainwater harvesting could work to reduce flood risk. It will do this through case studies in a flood vulnerable part of England around the city of Hull.

Rainwater harvesting is the process of collecting rain, in a rain butt, tank or pond and using it for another purpose like flushing the loo. Rainwater harvesting is a popular means of addressing drought, particularly in countries with chronic issues of water shortage. If many nearby properties undertake rainwater harvesting, however, it could also be an effective means of preventing floods.

Before our homes were built the rain that falls on our property would have soaked into the ground, or puddled and then evaporated. Now our roofs and drains mean that heavy rain flows very rapidly into the sewer. Sometimes the sewer is not big enough to cope with all the rain. If we can reduce the amount of rain on the roads and/or keep rain out of the sewer (or at least slow it down) then we might be able to prevent rain or sewers flooding homes, and sewers polluting rivers.

Many UK householders own and operate 'simple' water butts, typically using collected rainwater for garden watering during summer. For a water butt to help prevent flooding, spare capacity is needed at the start of the rain. This cannot be guaranteed for a manually-emptied water butt, particularly in winter, when gardens do not need watering. 'Smart' options have been developed to address this, for example, some discharge water slowly, while some are computer controlled and release stored water ahead of forecast rain. But this creates a potential difficulty: if we are asking households and communities to take on rainwater tanks, how are they going to feel if the water in 'their' tank is released without their say-so? This question concerning 'how will the water be controlled' is just one of many issues that might concern households who could be asked to take on a rainwater harvesting tank to help protect other people in their city from flooding. Households are also likely to be concerned about the appearance of a rainwater tank, where it would be, who would pay for it, and what would happen if it went wrong.

In this project we are going to work with the residents and community groups in two different areas near Hull - one richer and one poorer - but both in locations which contribute to downstream flooding problems. We will talk with households and community groups to explore whether, where and how rainwater could be stored in their neighbourhood to help prevent flooding downstream. In asking 'whether' and 'where' we would be considering whether there is space to put tanks or build ponds near their community buildings, in their open spaces or in their homes. In asking 'how' we would be exploring what sort of ponds or tanks, of what appearance, to whose cost, and under whose control. We will report our findings to the water company and local authority. If we find rainwater harvesting is feasible in the case study sub-catchments, the water company and local authority have agreed to go ahead and fit the devices according to our plan. Whether or not rainwater harvesting turns out to be feasible in these particular sub-catchments, our findings will contribute knowledge about when and how rainwater harvesting for flood prevention can fit in with people's everyday lives.

MOCA has the potential to lead to a step-change in UK urban stormwater management by providing robust scientific evidence to accelerate the widespread deployment of cooperative dual function RainWater Harvesting (RWH) to reduce urban flood risk and achieve wider benefits. Specifically, it will stimulate product innovation (change in RWH functionality and appearance), governance innovation (the design of dual function RWH mobilisation initiatives) and research innovation (new community research processes used to plan changes to water management).

To this end, MOCA will be implemented and disseminated in partnership with three sets of beneficiary stakeholders.

Water Governance stakeholders include local authorities, water supply and sewerage providers, water regulators and government. Like our Partner, the LWW Partnership, these stakeholders are concerned with fulfilling their statutory duties for the management of current and future water risks, but also with support for public wellbeing. These stakeholders will benefit significantly from MOCA's provision of the necessary robust evidence to justify and design initiatives for the widespread deployment of dual function RWH. Such deployment is important because RWH represents a practical and reproducible SuDS option, with the potential for extensive application in existing urban cores, especially where space is limited and ground conditions cannot accommodate infiltration. Specifically, MOCA will document how RWH will reduce urban flood risk while also contributing to drought resilience, enhancing household engagement with the water system, and reducing household water costs. Its 'cooperation models' will aid governance stakeholders in deciding which types of RWH to offer when and to whom, hence providing governance innovation. In addition, MOCA's research innovation of close community working also has the potential to influence the roll out of different types of SuDS and other mobilisations of active water citizens.

Development stakeholders include RWH manufacturers, housing association and housing developers. RWH manufacturers are centrally focused on the nature of RWH devices, and hence concerned with product innovation. Developers and housing associations are concerned with fulfilling statutory requirements for drainage, while also offering infrastructure that is reliable, attractive and financially beneficial to residents. New insights into public attitudes to RWH systems will provide development opportunities for new proprietary systems, representing an economic opportunity for UK contractors and suppliers. In 2014 the HTechO publication (UKWRIP, NERC and the GoST) reported that the country currently only had 3% of the global water market share, but in 2015 the UK Water Partnership Report (Future Visions for Water and Cities) argued that, with investment in basic knowledge generation and alignment between research and industry, this could be 10% by 2020 (worth £8.8bn) . Green Infrastructure (GI) technologies (including Sustainable Drainage Systems (SuDS) and RWH with SuDS functionality) could represent a significant component of this. The cooperation models will also support housing developers and housing associations in planning whether, when and how they should implement this new form of stormwater management.

Communities are concerned with the effective, attractive, low cost and low hassle functioning of their home and neighbourhood. MOCA's central concern is to understand and articulate the varied community needs so that RWH products and initiatives can be appropriately developed. The impact of MOCA will be to ensure that RWH benefits are optimised to help both the communities receiving RWH devices and those whose flood risk is alleviated through it. As such, MOCA has the potential to impact substantially on the drainage infrastructure of future homes in the UK and overseas, within which dual function RWH tanks may become a standard feature.