Bournemouth University archaeologists have discovered that the Dorchester aqueduct – one of the longest and most studied Roman watercourses in the country – was two kilometres longer than previously thought.

The aqueduct was a vital part of Roman life in Dorchester, supplying water for the town’s public baths, fountains and wealthy households. The discovery adds to existing understanding of Dorset’s history and how Dorchester, then known as Durnovaria, grew into a strategically important settlement during the Roman occupation of Britain.

The findings have been published in the journal Britannia.

“This aqueduct has been investigated by archaeologists for over a century,” said Harry Manley from Bournemouth University’s Department of Life & Environmental Sciences, who led the research. “Despite extensive examinations in the 1990’s, the source of its water and the upper sections of its course have never been conclusively mapped, until now,” he added.

Earlier studies have suggested that the source of the aqueduct, which followed a winding twenty-kilometre route up the Frome valley northwest of Dorchester, was a lake in Steppes Bottom. However new surveys and archaeological investigations as part of this new study found evidence that its route headed further upstream to the village of Notton on the river Frome.

Harry began his research by studying publicly available lidar data which allowed him to trace the elevation and physical features of the land upstream of Steppes Bottom. This suggested that the aqueduct followed a path further north. He was also able to compare this to a geophysical survey carried out by Bournemouth University during a previous study at Frampton Villa which lies further along this newly identified route, near Nunnery Mead.

“That geophysical survey revealed signs of a narrow channel running northwest to southeast. This matched up with my findings from the lidar data, so it seemed like the smoking gun that proved the aqueduct ran through the area,” Harry explained.

To confirm the presence of the waterway, the BU team carried out a ground penetrating radar survey and followed this up with a small excavation, during which they found evidence of the wood line aqueduct channel.

“Getting water supplied into prominent structures and buildings in the town would have been a sign of modern living at the time, and an indicator of the town’s status,” Harry explained. “For the citizens of Dorchester to have this aqueduct constantly providing them with fresh water would have been a matter of civic pride. Understanding more about how it was constructed and maintained, and where it began, adds further detail to this vital aspect of Roman life,” he added.