A shaduf (sometimes written 'shadouf' or 'shadoof', also called 'counterpoise lift' or 'well pole' or 'sweep') is a simple device for lifting water from a river, reservoir, cistern or shallow well. It is a long pole balanced on a horizontal beam. The pole has a bucket (or waterproof bag) suspended from a rope at one end, and a counterweight at the other end. To use a shaduf you simply lower the bucket or bag into the water, let it fill up, then raise it back up again; the counterweight ensures that the bucket is easy to lift even when it is full of water.