Due to a shortage of water in the Ipswich area in the 1960s, a list of twenty potential sites for reservoirs was made, with Alton being the chosen site.

The land was mainly farmland, but was also home to a mill and Alton Hall.

The mill was dismantled and reconstructed at the Museum of East Anglian Life in Stowmarket.

The pumping station and treatment works below the dam is capable of treating up to 10 million imperial gallons (45,000 m3) of water a day.

Between 85% and 95% of the water goes to Ipswich and Felixstowe via the Wherstead reservoir and the Orwell Bridge with the remainder fed to the villages of the Shotley Peninsula and south Suffolk.