Insights from our community downpipe disconnection projects
Hello! đ Iâm Ari, the Technical Director at Our Rainwater, and Iâm the guest author of this weeks blog post! Weâve been involved in quite a few community downpipe disconnection projects now, and weâve gained loads of valuable insights that weâre keen to share, to help you make your projects as successful and impactful as possible!
This week Iâll be sharing my top 5 âbrutally honestâ challenges that often get overlooked - ignore them and they can come back to bite you, but tackle them early on and you can turn them to your advantage!
âFreeâ water-butts arenât really free
Downpipe disconnection campaigns often look at installing âleakyâ (or attenuation) water-butts on downpipes, to slow the flow of rainfall into the sewers, helping prevent sewer spills, and storing some water for householders to use, reducing treated water demand.
These are often provided for free to target communities, so whereâs that money coming from? Like more traditional water-company infrastructure, interventions tend to get paid for out of householder bills or grants from the regulator. But unlike traditional infrastructure, these interventions are very visible to the public, so come with the power to influence what consumers think about you.
This can be great if you get it right - a solution that householders understand is helping them save money on their bills and protect the environment from pollution can be a great reputational boost - but if you get it wrong it can re-enforce poor public perception.
Spend the time to think about how you engage your communities, and give them a solution that theyâll value and appreciate, and youâre getting ahead of the reputational risks!
Communities are a great asset, and your responsibility
With regulatory compliance becoming a bigger and scarier challenge for water utilities, itâs easy for them to forget that their core purpose is to manage water for their communities. Communities really want us to get this right - they want to stop sewers overflowing, drought control measures, and rising prices - and engaging with them directly is a great way to work together towards these common goals.
But, as a water utility, you canât ask your community to help you deliver your goals if youâre not going to work with them to deliver theirs. This is even more pertinent when youâre asking them to put infrastructure on the downpipes in their garden!
Start with understanding your communities wants and needs, what are their priorities, why should they engage with you, and how can you best address their concerns? Then make sure that your interventions really deliver on their priorities, and remember that theyâre often very closely aligned with your regulatory compliance goals.
If you get this right you can get communities using water in their water-butts regularly (reducing demand and runoff), maintaining their water-butts to keep them working, engaging with the water challenges weâre facing under changing climates, and even sharing your sewer misuse reduction messaging.
If you get this wrong you can spend a lot of money installing solutions that donât work for the people whose gardens youâre putting them in, that get abandoned, removed, or vandalised, whilst creating a whole lot of ill-will.
Install the right solution
This sounds incredibly obvious, but make sure that the intervention that youâre installing actually does what you want it to do. I cannot tell you how many schemes Iâve seen that install an intervention that has barely any impact on runoff rates because they drain too fast, or that can help reduce flooding in a 1-in-50 year storm but will have almost no beneficial impact at all for the other 49 years!
These interventions work by holding back water that rushes off the roof in heavy rain and slowly releases it into the drains, turning that big peak flow that surcharges drains into a nice slow uniform flow that drainage infrastructure can handle. If your intervention drains too fast then that rain from the roof just pours straight through it, not slowing it down at all, and your drains flood. If your intervention drains too slow then the tank fills up and overflows, with all that excess going straight back into the drains, and your drains flood.
Optimising these drain rates does require a bit of thought, you need to have a good idea of the sizes of the roofs that youâre draining, the nature of the rainfall youâre expecting, and how the different solutions perform. But this is very doable, and by ignoring it youâre potentially spending a whole lot of money on a whole lot of nothing
But donât just trust the shiny marketing
As more water utilities catch-on to the benefits that community rainwater management schemes can bring, the market for possible interventions is growing. This is absolutely brilliant, as the pool of different products for schemes to choose from is growing by the day. Good schemes donât just pick one, they pick a few, to fit the different requirements of different households, communities, and drainage systems!
But with a growing market comes growing marketing. All of these suppliers want you to pick their solution to install, and if youâre a utility with a customer-base of tens of millions, thereâs a lot at stake, and a lot of money being spent on influencing you.
The most egregious marketing scam âpufferyâ is around smart water-butts. These sound incredible - computer controlled water-butts which release water based on forecasted rainfall, so that thereâs always space for incoming rain, and always water for householders to use in the garden when they need it. However, this computer-wizardy doesnât come cheap. The units themselves cost ÂŁÂŁÂŁÂŁs to buy and install, have recurring running costs for data transfer and maintenance, and are much more complex to maintain than a simple slow-drain system.
And is it really worth it to be able to control just 250L of storage? In a word, no. Most householders re-use just ~500L of water per-year, so each litre may well be costing you ÂŁÂŁs, whereas a âleakyâ attenuation tank can cost literally 1/1000th as much. And if a âsmartâ water-butt gets an inaccurate rainfall forecast it can actually make flooding worse rather than better!
Donât take my word for it - look at case-studies, run some simulations and see how different interventions perform, and make sure that youâre spending your customers money wisely!
Thereâs no silver bullet
Having done all that hard work to choose the right intervention, you can just keep installing it in every community in your area, right? Iâm afraid not!
Ultimately you need your interventions to meet your objectives, be that reducing CSO spills, reducing water demand by providing water for re-use, or helping tackle surface water flooding. Your objectives will be different for different schemes and locations, so naturally your desired outcome will change too, and the right tool for the job is very likely to be different.
Secondly, different catchments can be drastically different. You might have a combined sewer on one street where sewer overflow is a risk, and the next street along might have separate sewers where storm-water runoff isnât a priority. Or you might have thick clay subsoils in one town, reducing infiltration rates and creating surface water runoff problems, and permeable chalk bedrock in the next town, where your challenge is actually your chalk streams drying up!
And finally, the most complex variable of all, no two communities are the same. Different people have different motivations and drivers, different requirements and priorities, and even different house layouts that suit different types of intervention! In some communities you need a narrow and unobtrusive intervention that can fit in narrow walkways between houses, and in some communities you need a pretty rainwater planter that takes pride of place in front-gardens, full of plants and flowers.
