Visitors to an innovative green space in Earley near Reading will be walking on water when work on a new underground reservoir officially finishes this week.

The tanks of Thames Water’s award-winning reservoir in Elm Lane are completely covered in grass, trees and wildflowers to form a hill which merges with the adjacent open parkland.

Temporary fencing in place throughout the construction and landscaping periods will be removed on Friday for the official opening event.

The £6 million reservoir, which serves 100,000 people, will meet increasing demand for the next 30 years and holds enough drinking quality water – 14.6 million litres – to fill five-and-a-half Olympic sized swimming pools.

Thames Water production manager Gareth Parry said:

“Reading is an ever-growing town so it’s vital we carefully plan our water resources for the future. Earley reservoir will help make sure there is enough to meet demand, especially during peak periods.

“As it’s so near to homes, we’ve done all we can to put the area back to how it was before we started, and we’re really pleased with the result. Once everything grows we’re confident those who use the park won’t even know they’re walking across the top of a container holding millions of litres of drinking water.”

Water is piped into the reservoir from Fobney water works, approximately two miles away in Rose Kiln Lane. Since being hooked up to the Thames Water network in the spring, the underground reservoir has been working alongside the neighbouring 1970s-built reservoir to supply homes in Earley, Lower Earley, Woodley and south Reading, as well as a number of schools, businesses and Reading University.

In June, the project was recognised by the Institute of Civil Engineering for engaging with local residents and keeping them up to date on progress during construction.