This is the last surviving privy at Masson Mills. There was one privy on each floor of the mill from Arkwright’s time right up to 1911. This is the last one which has not changed.
The “contents” of the privy fell straight down into a tunnel underneath the mill through which water was always flowing, which flushed the waste straight into the River Derwent. Also when it rained, a pipe sent rainwater down to flush the waste pipe.
In Arkwright’s time Masson Mill employed over 550 people, so there would often have been a queue to use the privies!