It will connect 34 of the most polluting combined sewer overflows (CSOs), via transfer tunnels, and was expected to reduce the number of overflow events to a maximum of four per CSO per year at time of commissioning, although increasing gradually due to effects of climate change and population growth. The tunnel will transfer the captured sewage to the Stratford to East Ham part for onward delivery to Beckton Sewage Treatment Works for treatment. The recycled clean water will then be released into the River Thames.