Rain Gardens - What’s in a planter?

SuDS features as part of a drainage strategy take on many forms, often being led by drainage engineers they can focus on water quantity and quality as its a challenging issue in many schemes. Sometimes what gets overlooked is the amenity and biodiversity benefits that well-coordinated designs can offer.

Enter the rain garden. Fantastic surface-level bio-retention components that can take many forms incorporating inlets, widen your choices of soft landscaping, or simply be a lined plant pot with an overflow. They suit both urban and natural environments, and with an infinitely variable scale they’re suitable on an individual rain water pipe all the way up to draining public highways.

What’s the aim?

Providing a rain garden contributes a water treatment stage to the SuDS management train, and enhances biodiversity through the planting mixes used - attracting insects, bees, birds and other critters. A well planted rain garden adds visual amenity to any space.

How do they work?

Rain gardens can either capture water themselves through an integrated inlet or be fed by an external pipe - a rain water downpipe from a roof for example, making them an excellent choice alongside buildings.

Water percolates down through a layer of free-draining subsoil stripping out suspended contaminants, usually being collected by an underdrain and being directed to the drainage system. For heavier rainfall an overflow is usually provided just below the surrounding ground level.

And the pitfalls?

Of course, nothing is perfect. But being simple features there’s not too much to go wrong and the maintenance isn’t a whole world away from what’s required for any planted bed. It’s important to clear heavy leaf fall and other debris to prevent blocking overflow pipes and long-term there may be a need to refresh the soil.

We’ve designed many rain gardens and each is unique. They can be designed as a focal point or with very common parts and materials meaning construction and maintenance costs don’t have to be a worry.

Get in touch if you want to consider rain gardens in your next project and we’ll happily walk you through your options.