Rain Harvesting & Water Security in Urban Areas

Many cities across the world provide their residents with access to “mains water” – water that is supplied to a number of properties from one central location. However, not all mains water supplies offer a ready and reliable source of water.

Population pressures, conflict, political upheaval, accidental contamination, poor resource management and other challenges can restrict the availability of mains water. In extreme situations, it may become completely unavailable for extended periods of time.

In these situations, rain harvesting can offer a level of water security for your household that the city’s infrastructure cannot provide.

In 2013, the United Nations (UN) defined water security as “the capacity… to safeguard sustainable access to adequate quantities of acceptable quality water”. It also noted that a key aspect of water security is preserving ecosystems, as environmental degradation can cause or exacerbate problems with water security.

As water is not only necessary for human health and wellbeing, but also for sustaining livelihoods and even socio-economic development, a threat to any aspect of water security is a serious issue. Unreliable mains water supplies obviously do not meet the water security brief. Instead, they can compromise water security for individual households and entire cities and regions.

By addressing all these issues, rain harvesting is one viable solution to the challenge of water scarcity that can be implemented at a household and/or neighbourhood level. This is in harmony with the UN’s acknowledgement that it is sometimes necessary for investment in water security to occur at the local or micro level, and that solutions to water security challenges will not come from the public sector alone.

A properly designed Rain Harvesting System can provide a plentiful supply of clean water for use in and around your property – or for you and your neighbours, if you choose to pool your water resources in this way. This offers a level of water security by providing a reliable supply of water when other supplies aren’t available.

Rain Harvesting also contributes to water security by helping to protect the local environment. Rainwater runoff from roofs can cause erosion, degradation to natural waterways and even flooding. Harvesting and storing rainwater, on the other hand, prevents this damage from occurring.

In its 2017 report on water scarcity in North Africa and the Middle East, the World Bank suggested three potentially complementary approaches to overcoming water scarcity and insecurity. One of these was to provide more water to meet demand.

Among its suggestions, the World Bank noted that while Rain Harvesting systems already provide an important water supply for many rural communities, urban rain harvesting will become increasingly important for ensuring water security in urban areas, particularly in the face of growing urbanisation.

The key goal of Rain Harvesting is to harvest and store cleaner water and lots of it. This reflects the UN’s water security definition of “adequate quantities of acceptable quality water”. Achieving this goal means going beyond the simplistic approach of adding pipes between your gutters and tank. Instead, it involves applying the Rain Harvesting System Design Pillars to filter, divert and otherwise protect the water you harvest. This means using rain heads and/or Maelstrom filters to filter leaves and debris from your water, using first flush diverters to isolate and discharge contaminated water, and securing your rainwater tank with appropriate screens and covers to protect the rainwater you harvest. You can see examples of systems that apply these pillars here.

While many Rain Harvesting systems are installed on individual houses, it may also be possible to pool your resources with your neighbours by installing a common rainwater tank that stores water harvested from several different homes. Obviously, this puts the burden of maintenance on everyone’s shoulders, but it can be an effective way to lower the costs associated with the most expensive aspect of any rain harvesting system: the tank.

Want to learn more about designing a Rain Harvesting system to meet your water security needs? Click here to download the Rain Harvesting Handbook.