What does the future of Rainwater Harvesting look like?

My vision for rainwater harvesting starts with every new development including rainwater harvesting as standard. Whether that be a commercial, non-household development, or a large new housing estate, every development should include this important technology.

Why? Reducing stormwater runoff at the source is one of the simplest ways to free up capacity in our combined sewer network. A traditional attenuation system simply slows down the volume of stormwater runoff into the drainage network; however, a rainwater harvesting system stops the majority of rainwater entering the drainage network as the water is used as a sustainable water supply.

Rainwater harvesting is not just beneficial for reducing runoff, the technology tackles water scarcity issues too. Water scarcity is a huge issue and it is important to remember that water companies have no legal obligation to supply water to non-household customers. It is in a business's best interest to use water wisely!

Me and my team are seeing more scenarios where rainwater harvesting was value-engineered out during the construction phase. Now, the end user of the building is coming back to us to retrofit a rainwater harvesting system at considerably more expense than it would have been to include at the new build stage. Don't get caught out.

Community Systems

Having been in the industry for over 20 years, I have had experiences in both commercial and domestic rainwater harvesting systems. Whilst individual home domestic rainwater harvesting systems seem like a great idea on paper, they are difficult to maintain in reality. A rainwater harvesting system should receive two service visits per year, and, with individual home systems, the maintenance falls to the homeowner. However, maintenance providers like us still have to charge for service visits at a commercial rate; therefore, maintenance becomes too costly for the average homeowner.

A couple of years ago, I was thinking about how we could overcome this issue. This is where I came up with the concept of the community rainwater harvesting system. One system collects roof water runoff from multiple homes into a central storage tank and then boosts the rainwater back to every home as a sustainable water supply.

Community systems are a lasting piece of infrastructure and take up zero space within a home. They can be centrally maintained by just one engineering visit rather than an engineer having to service many systems on an 800-home development.

This type of system also mitigates the need for homeowners to change their water consumption behaviour. Homeowners would also not be able to switch off the system or remove the system through an illegal mains water bypass. For water companies, community systems can be centrally monitored and ensure the system is still providing the intended benefits.

Community rainwater harvesting systems can also contribute towards on-site attenuation capacity. Our system can be combined with Met Office Weather Data to ensure 100% of attenuation capacity is available for the site for an incoming storm. I would like to see these technologies as standard on all newly built properties.

Housing developers can benefit too. Instead of installing large attenuation ponds, they can install crates or an underground storage tank, allowing them to build more homes.

I have had many discussions with people in the industry about the 'fittings' approach. Essentially, this means the installation of water-saving devices within the home. Think low-flow showers and flow restrictors. However, these can be simply removed by homeowners and there is no guarantee that they will be reducing water consumption 10 years after construction. Rainwater harvesting is a lasting piece of infrastructure.

Maintenance

Community rainwater harvesting systems can be adopted as an asset by an estate management company. Our estimations show that for a housing development of 50 homes, maintenance costs for individual systems would be around £5850 collectively. With a community system serving 50 homes, maintenance would only be £13 per home, per year.

Alternatively, NAVs and water companies could adopt the systems as an asset and charge a lower rate for a sustainable water supply to cover the cost of maintenance. Unfortunately, legislative barriers prevent NAVs and water companies from adopting rainwater harvesting systems but as an industry, we are campaigning for change.

I am also happy to hear other suggestions about potential adoption solutions.

My Experiences

A word of caution based on my experiences. Unfortunately, whenever we see legislation on increased use of rainwater harvesting, many new suppliers start offering rainwater harvesting systems. This creates an issue as the systems must be maintained properly and new entrants often lack experience in maintaining rainwater harvesting systems resulting in a design that does not consider the end user. They then very quickly pull out of the market and it is left to experienced companies to pick up the pieces of many maintenance issues.

My advice would always be to check the pre-tank filter of the rainwater harvesting system can be maintained by one engineer from ground level. Also, ask if the break-tank storage capacity is sufficient as this is the biggest reason for systems failing. Break tanks on a rainwater harvesting system should have a minimum of an hour's worth of backup capacity. Anything over an hour is not a bad thing! Cheaper systems will often have an undersized break tank which cannot keep up with the total water demand.

The best rainwater harvesting systems will be specified with automatic backwashing to prevent the need for the physical replacement of a cotton wound filter by the end user. UV filtration should also be included where there is potential for rainwater to create an aerosol.

Summary

It is certainly an exciting time to be in the industry! We have many research and development projects ongoing which will improve our systems even further, including the integration of artificial intelligence with rainwater harvesting to monitor and advise on best usage.

Ultimately, I am here to help. Please contact me for any questions or advice.