A water snake is longer than an adder by half, as long as a Human’s arm to their height, and slimmer for its length. It is olive-green or grey-brown with small dark bars along its sides and a yellow-and-black collar behind the head. Its eyes are round, with round pupils. The heath adder, by contrast, is short and thick, zigzag-backed, with a slit-pupilled eye.

It swims well, head held just above the surface, and suns itself on banks and reed mats. Caught, it hisses and writhes and lets out a foul-smelling musk, and sometimes plays dead with its mouth open, which convinces nobody who has seen it.

Water snakes live in ditches, ponds, fens, and reed islands throughout the low wet country of the Confluence Basins, the Reedmere above all, and along the backwaters of the Lower Serath.

A water snake hunts frogs, toads, newts, and small fish in the water and the reed edges, swallowing them whole. It is shy and flees from people. It does not bite unless handled, and the bite does nothing worse than a scratch.

In early summer a female lays a clutch of eggs in a warm heap of rotting vegetation, a dung heap, or a reed pile, and the young hatch in autumn. Water snakes sleep through winter in banks and under roots. They may live fifteen years.

They give nothing to people but fewer frogs. They are harmless; the danger is the mistake, and a farmer who learns to spare water snakes may one day spare an adder.

Reedfolk spare water snakes as part of the fen they belong to, and tell children the difference between the snake of the water and the adder of the heath as one of their first lessons: the round eye and the slit eye, the long slim body and the short thick one, the collar and the zigzag. Basin farmers say any snake in the barn means a death, and kill it. Some Reedfolk households keep a water snake’s shed skin above the door against fever.