Coordinates: 52°27′50″N 0°02′13″E / 52.464°N 0.037°E
In the drainage schemes of the Fens of Eastern England, some of the principal drainage channels are each known as the Forty Foot or Forty Foot Drain, the name being qualified when there is a need to distinguish between them. They are Vermuyden's Drain, South Forty Foot and North Forty Foot.
The Forty Foot Drain, also known as Vermuyden's Drain, is an artificial drainage river in Cambridgeshire, which is one of the key elements in the draining the Middle Level of the Bedford Level, in the Cambridgeshire part of the Fens. It was instrumental in Sir Cornelius Vermuyden's great drainage scheme of 1649-53. Located near Chatteris and Ramsey, the river runs 10.5 miles, from Wells Bridge, where it joins the old River Nene, to Welches Dam Sluice, where it joins the Counter Wash Drain, which then changes identity, becoming the Old Bedford River. These junctions are at grid references TL300880 and TL470858 respectively. When the drain was newly made, its western end was in Huntingdonshire. The waters of the Forty Foot Drain no longer discharge through Welches Dam Sluice. Instead they flow via the Sixteen Foot Drain to Three Holes and thence via the Middle Level Main Drain and the pumping station at Wiggenhall St. Germans to the sea. The Sixteen Foot Drain connects to the Forty Foot drain above Horseway Lock.