There was a rare opportunity to get a glimpse inside a 150-year-old Victorian reservoir underneath Norwich this week. Our engineers have been carrying out an inspection and clean of the Sultzer Reservoir, one of two underground, treated water reservoirs originally built in 1871 which are still used to supply the city today. Between them they store 12 million litres of drinking water as it makes its way to customers’ taps. Their size means it would take almost three years to fill one of them using a normal kitchen tap. As part of a routine maintenance programme, we're inspecting the structure to ensure it's kept in tip top condition and can continue to supply safe, clean drinking water to customers in Norwich for years to come. Over 500 underground treated water reservoirs are used by Anglian across the East of England. Unlike the large surface water reservoirs like Alton and Rutland, which store river water before treatment, underground storage reservoirs hold clean drinking water and provide resilient storage at points across Anglian’s 38,000km network of water pipeline.