When we think of miniaturization, we tend to think of modern electronic products, not Edwardian waterworks.
At its height, Twyford Waterworks occupied three large buildings: a pumping station, a set of limekilns and a water softening plant. These days Southern Water use just one room in the old pumping house. This houses the wells, together with the switch gear and controls for the modern submersible electrical pumps installed in 1980 at the bottom of the wells.
The Diesel House
Going back in time, occupying a large addition to the pumping station built in 1934-35 and a shed outside, are the three big Rushton diesel engines driving Gwynne centrifugal pumps that the electric pumps replaced. These are being restored, and one of them, a 3VCR, is currently operational.
The Hathorn, Davey & Co
Originally, pumping was carried out by two huge triple expansion steam engines. One of these was removed to make space for the electric pumps, but the other one, made by Hawthorn, Davey & Co. of Leeds in 1912, is still in place, as are the three Babcock and Wilcox boilers that powered them.
At the time of my visit (2014) the boilers were in the middle of a massive restoration programme, as the result of a Heritage Lottery Fund grant. They were covered in scaffolding, making them difficult to photograph. Needless to say, with no steam, the engine was only on static display. One to go back to, once it is back in operation.
The Lime Kilns
The other two buildings house the equipment used to soften the hard chalk water and to filter the supply.
In 1969 with the introduction of modern detergents, it was no longer felt necessary to soften water at source, and lime water softening became redundant. All over the country the equipment was scrapped. Twyford is now home to the only substantial remains of lime softening equipment in the whole of Britain.
An Hydraulic Engine
Chalk was dug from a pit behind the pumping station, and hauled up to the lime kilns on an incline powered by a simple hydraulic engine. There it was burnt to form quick lime which was mixed with water in a mixing tank powered by another hydraulic engine to form slaked lime.
After further dilution it was added to the freshly pumped water, and fed into a large settling tank in the filter house. There the dissolved calcium bicarbonate, which gives water its hardness, was precipitated out and settled as a sludge on the bottom of the tank.
The Haines Filters
The water was then passed through a set of Haines filters to remove any remaining particles. The filters original installed at Twyford were scrapped, but a replacement set were were moved here from Wimborne Waterworks as part of the restoration. There is a display of some smaller engines and pumps moved here from other sites in this building.
The narrow gauge railway which was used to move lime and other materials around the site originally relied on muscle power alone. This has now been extended and is home to some industrial locomotives. The top end of the site is now a nature reserve.
The site is only open on a limited number of themed open days throughout the summer months. Check the events page on the official web site detailed below for details.