Waterways charity the Canal & River Trust is installing two large three-ton pumps at Gloucester Pumping Station in Gloucester Docks this week.

The new energy efficient pumps join the two existing ones to play a crucial role in managing water resources in Gloucester and Bristol.

Water levels in the docks and canal are constantly managed by the Canal & River Trust otherwise levels would fluctuate due to lock and dock operation and abstraction.

The pumps at Gloucester Pumping Station take on an average of 100million litres of water per day from the River Severn to keep the Gloucester & Sharpness Canal open for navigation and ensure correct water levels for ships using the busy port at Sharpness Docks.

Their role doesn't end there - the water taken from the river is treated at Purton, to be used by nearly half the 600,000-strong population of Bristol. The canal has supplied drinking water to the city since the 1960s.

The new Flygt column pumps are more efficient, have a higher level of resilience and have been designed to be easier to maintain, helping their sustainability and giving them a life span of around 20 years. It's expected that the new pumps will cut the electricity bill for the pumping station by around 10 percent.

Each pump weighs more than three tonnes, is the size of a small car, and requires a 40 ton road crane to install. They cost £100,000 each and are capable of filling an Olympic size swimming pool every 21 mins.

The trust said the pump replacement project forms part of wider activities to reduce energy consumption and CO2 emissions.

Nigel Taylor from the Canal & River Trust said: "These pumps act like a beating heart in Gloucester Docks for the Gloucester & Sharpness Canal. Though tucked underground and unseen they are controlled by our state-of-the-art waterway management system to continuously manage water levels in the canal.

"We are grateful to the players of People's Postcode Lottery as the existing pumps were reaching the end of their working life, and funding raised by the lottery players has made these new ones possible. At a time when our waterways are busier than ever the pumps really are mechanical and technical heroes - keeping the canal open, ships moving and Bristol's thousands of taps running with water."

Laura Chow, head of charities at People's Postcode Lottery, said: "I'm delighted that support from players will see new, more energy efficient pumps being installed so water can continue flowing along the canal for boats, ships and Bristol residents alike.

"Players of People's Postcode Lottery are supporting this project as part of our Postcode Climate Challenge initiative, which is providing 12 charities with an additional £24 million in funding for initiatives tackling climate change this year."