Sewage is being pumped into rivers across Hertfordshire, but which of the county's waterways is worst affected?

Using, which shows data collected through Event Duration Monitoring by Thames Water, real-time updates of sewage discharges can be recorded.

Historical data of these discharges is also recorded, which provides a shocking picture of how much sewage is being pumped into the county's rivers.

Among the worst affected is the Grand Union Canal, with sewage discharged into the waterway near Hemel Hempstead for a total of 612 hours since the start of this year.

This then flows down through Watford, before joining with other rivers where sewage is being dumped and continuing past London and down into Surrey.

Among the waterways that joins this sewage stream is the River Ver, which runs through St Albans and Watford where it becomes the River Colne, which has seen 65 hours of discharging.

The worst by far though, is Cottered Brook, which flows to the east of Stevenage down through villages including Walkern, Aston and Watton At Stone.

Since January 1 alone, sewage has been pumped into the water at Cottered for a scarcely believable 1,754 hours, continuing on an almost daily basis since the beginning of February.

The rare chalk stream of the River Mimram - which starts out at Whitwell and flows through Digswell and Welwyn - is another badly impacted, with 169 hours of discharge this year.

The River Lea has seen more than 313 hours of sewage discharge at multiple points along its course, including 120 hours in Harpenden and 116 hours in Mill Green.

The village of Essendon has also become a hotspot for sewage discharge, with 34 hours into the River Lea and 89 hours in Woodhill Brook.

There is also further discharging at smaller sites at Potters Bar Brook (1 hour and 40 minutes) and Codicote Groundwater (four hours and 15 minutes).

Among the rivers that show no sewage discharge are Hitchin's River Hiz.