£220,000 project under way to restore 200-year-old water-saving canal engineering

Each movement of boats through locks uses thousands of litres of water, which must be replenished from reservoirs, river flows, boreholes or other sources.

Georgian engineers understood this problem, and, in 1815, some 20 years after the flight of six locks at Hanwell, West London, was built as part of the then Grand Junction Canal between London and Birmingham, side ponds were constructed at each lock.  

These meant that when the lock chamber emptied to lower a boat down to the next level of the flight, instead of the water being lost to the lower canal pound, paddles connecting the lock to the side pond were opened and it was “put aside” and stored to assist in refilling the lock.

But over two centuries, these ingeniously frugal - but ultimately non-essential - features fell into disuse and disrepair, in a world where the overuse of resources became commonplace. 

In 1975 the Hanwell flight of locks and brick boundary wall of St Bernard's Hospital were listed as a Scheduled Monument, with the then Royal Commission on the Historical Monuments of England noting the presence of side ponds at every Lock from 92 to 97 in the citation. 

Fast forward to 2025 and such careful conservation of water supply has never been more relevant, with the Canal & River Trust forced to introduce a number of navigation restrictions over the summer to prevent the 2,000 miles of waterways the charity cares for from running dry.

The Hanwell Flight of Locks repair and restoration project is being funded by Historic England’s regional Heritage at Risk repair grant to clear, stabilise and restore the derelict side ponds at Locks 94 and 95, demonstrating the genius of the early canal engineers.  

While this project itself – with a £180,000 grant from Historic England, £5,000 from the Inland Waterways Association and the remaining contribution from the Trust – is not intended to restore the side ponds at Hanwell to operational use, it could inform any such project in the future, and point the way towards how inland navigations might make better use of increasingly precious water resources. 

The programme of conservation brickwork repairs will include a week-long “Canal Camp” by the Inland Waterways Association (IWA) Waterway Recovery Group and training sessions with the Trust's volunteers led by contracted conservation brickwork specialists in spring and early summer next year. 

The project will create a more beautiful space, offering improved physical and mental wellbeing, educational opportunities, and local pride. It builds on the Southall Wellbeing Way and complements the proposed Ealing Regional Park, embedding the historic waterway within a wider green infrastructure network. Ultimately, the project will leave a lasting legacy of environmental stewardship, civic engagement, and heritage conservation.  

Our heritage advisor Phil Emery said: “It’s hard to overstate the historical importance of these side ponds, situated on a stretch of what is now the Grand Union Canal that has been immortalised by the painter JMW Turner and which offer a direct connection to the engineering prowess and foresight of the Georgian canal builders. 

“The clearance of vegetation and silt from the ponds at Locks 94 & 95 under archaeological supervision will give a better idea of the scale of any structural damage and inform the later stages of the project.”