Modern Londoners take for granted their ready access to clean water. Their medieval ancestors could obtain water from the Thames and its tributaries, not to mention springs and wells, but they also faced issues with pollution and droughts, and even risk to life and limb: Nick Higham notes that some poor souls drowned while drawing water from the river. Meanwhile, owners of riverside wharves and stairs often tried to charge a fee for the privilege of bringing a bucket to the shore. Piped water, thankfully, was delivered by ‘conduits’ to the heart of the capital in the mid-13th century. Nonetheless, the idea that every single home in the metropolis might enjoy constant flowing water, on tap, would have seemed utterly fantastical to our medieval forebears and, indeed, remained rather fanciful until the late 19th century. The story told in The Mercenary River is of how that dream became a (commercial) reality.

Work on the Great Conduit, London’s first piped public amenity, began in 1236 under the auspices of the City Corporation. It conveyed clean water from springs situated near Tyburn (the area around Marble Arch) to the City of London. The springs were a gift from Gilbert de Sandford, intended to provide water ‘for the poor to drink, and the rich to dress their meat’. A reservoir was built at the head to supply pressure and ‘conduit houses’ from which the public could draw water were established at intervals along the way. There were eventually sixteen dotted throughout the city, remembered to this day in a handful of quaint street names – White Conduit Street, Lamb’s Conduit Street, Conduit Mews and so on. But these limited facilities could not keep up with the requirements of a growing metropolis. London’s burgeoning population required water for cooking, washing and cleaning. Businesses and industry, likewise, all had their own particular needs. London’s first commercial supplier, the London Bridge Waterworks, began providing water in 1582. Instead of relying on reservoirs and gravity, the company introduced a mechanical system – a pump driven by a water wheel, powered by the tidal Thames. Nonetheless, supply to private houses remained scant and some took the law into their own hands. Higham notes how in 1621 water carriers petitioned Parliament against the endemic illegal tapping of conduits with ‘private branches and cockes’, which substantially impeded their capacity.

An important improvement was the creation of the New River, a canal bringing fresh water from Hertfordshire to the New River Head in Islington, completed in 1613 with the support of James I. The canal was a monumental work of civil engineering. It was created, as Higham explains, by