The museum tells the story of London's water supply using the original steam pumps as the main theme. Few can resist the drama as the 90 inch (2300mm) piston whisks the 42 tonne balance weight nearly 3frac12; metres upwards, to be followed by a pause, then the slow descent as two cubic metres of water are delivered, another pause, then the cycle beginning again as the weight shoots upwards. All this on an engine still in its original 1846 condition.
The oldest building on the site was put up by the Grand Junction Water Works Company in 1838 to house its new steam pump and two similar pumps purchased from Boulton, Watt and Company in 1820 and now to be transferred from the older pumping station at Chelsea. These three engines were modernised after the 90 inch engine, purchased from Cornwall, had shown what could be achieved in fuel economy by using higher steam pressure - 40 psi. When further capacity was required in 1859, the Bull type 70 inch engine was installed, followed by the conventional 100 inch beam engine in 1871 All these engines are still in their original positions. Four are currently in steam. These engines survived, and worked till 1943 because, in the last three decades before the Metropolitan Water Board (MWB) was formed in 1902, the old private water companies had no incentive to improve their pumping plant. When the MWB took over, they put all their efforts and capital into keeping up with increasing demand and retained the old steam plants in service. World War II changed this. Electric power supplies were laid on to London's pumping stations which enabled a switch from the labour intensive and fuel hungry steam plants to modern electric pumps. The steam machinery was shut down and scrapped to aid the war effort. All except one - Kew Bridge works. Its collection of six Cornish cycle pumps was quietly moth-balled. Clearly these survivors from the previous century had friends in high places. The MWB didn't make a big feature of their museum collection. It was quite difficult to get in and it certainly wasn't advertised. The change from MWB to the more commercially based Thames Water Authority in 1972 might have jeopardised the future had not a talented group of engineers, accountants, teachers and like-minded others appeared. This group had cut their teeth restoring the 1812 and 1845 beam engines at Crofton, fifty miles to the west of London, and were looking for a new challenge. They found it at Kew Bridge. By November 1975, the remaining 1820 engine was running, to be followed by the 90 inch eight months later. Rotative pumping engines were brought from elsewhere and installed in the former boiler house. Then the 1839 Maudslay was restarted in 1985. The Bull will be presented next year after eight years work. Restoration of the beam engines to an operating condition had been fairly straight forward but the Bull has thrown up a redesign problem which requires further work. The Water for Life Gallery, telling the story of London's water supply, was installed in 1997 with the aid of grants from the UK's Heritage Lottery and EEC funds. Other grants have been received to restore the Grade 1 listed buildings
No aid is received for day-to-day operation of the museum. We have to earn enough money to pay the running costs, including the few paid staff and the substantial gas bill of pound;25,000 per year. Without the unpaid efforts of our volunteer drivers, guides, maintenance workers and gardener, the Museum could not survive in its present form. A great deal of skill is required to drive a Cornish non-rotative engine. Cleaning and maintaining them is heavy and demanding work. The future will depend on us being able to attract and train the future volunteers. When Thames Water needed to conserve their two enormous triple expansion engines in the Scheduled National Monument at Kempton Park, the Kew team was approached. The Secretary, an accountant who had started both Crofton and Kew, readily accepted the challenge but recognised that he could lose all his volunteers at Kew if he let them loose at Kempton Park. A new wholly volunteer group was formed and, with some advice from Kew, succeeded in steaming one Kempton engine, weighing 800 tons and standing 62 feet tall. Charles, Prince of Wales, inaugurated that Museum in 2004. Operating such a big engine at off-design conditions has thrown up many unexpected problems - bearings, valves, cooling water, steam supply. Restoring these very large stationary engines for our visitors to enjoy has been a great success story, in spite of the formidable odds against us.