Wisley is the Royal Horticultural Society’s flagship garden. Set within 240 acres, it’s one of the UK’s best-loved and most visited gardens, attracting around a million visitors annually. Their outstanding horticultural displays and advice service are backed by a world-class scientific research team.

The concept desire for a new rainwater capture lake was to create a new, beautiful waterscape that met the RHS’s sustainability objectives, would support long term biodiversity and was environmentally friendly in its construction.

Clear Lake was cleverly designed to collect the rainwater runoff from the RHS Hilltop main building roofs and surrounding paths, providing vital irrigation for the surrounding 10-acre Battleston Hill woodland garden during periods of drought.

The resulting lined lake can retain up to 9,000m3 of water, allowing for up to 7,000m3 of water to be extracted during dry periods. It features a central Otterbine aerating floating fountain, supported by five oxygen pumps, with aquatic plants naturally absorbing unwanted nutrients to maintain water health. The lake sustains a plethora of plants and biodiverse wildlife.

During its construction, all excavated materials remained on site in order to minimise the environmental impact of the project and helped keep costs to a minimum.

At this scale, the earthworks planning element had to be precise in order to manage the soil movements for maximum efficiency and avoidance of double handling. Tackling this challenge starts with detailed 3D models of the site to determine where the soil cut and fill material will go. For instance, topsoil is the first element to be lifted and the last to be laid, ensuring that this excavation is put in the right location at the start, will ensure the project is completed with maximum efficiency at the end.

From the 3D models, diagrammatic plans are produced for the site team to implement. However, understanding and reading the materials as the earthworks are handled is imperative to the project’s success which is where the on-site team, with specialist skills and knowledge, deal with any ad hoc ‘sorting’ issues as they arise.  Issues such as sand or clay pockets, back filling, sealing banks and blending the lake into the landscape were all expertly managed by the team.

A grand opening was held in May 2023 by Marit Mohn, Clear Lake benefactor, and her granddaughters Clara and Aurelia celebrating this incredible transformation.

RHS Wisley Head Curator, Matthew Pottage was delighted with the result and gave us this highly complimentary testimonial:

“Miles Water showed an impressive level of competence and ability, from the day we met them, through to the completion of our new lake at RHS Garden Wisley. None of the RHS team had created a lake of the scale we were planning, and the guidance, support and easy-to-work-with approach from Roger and his team were much appreciated. We have a new feature that supports our sustainability strategy, but also looks great in the landscape and we are most grateful to Miles Water for this wonderful result.“