The sampler ‘Watertrap’ has been designed to take representative samples from running water up to a depth of approx. 25 meter. Samples are taken with the stainless steel device by catching part of a horizontal moving column at a certain moment at a certain depth. The sampler is lowered by means of a hand winch fitted with a steel cable. The winch is fixed to a telescopic arm. The fastening clip of the telescopic arm allows fixing of the arm on the railing of a bridge or a boat. The depth at which the sampler is located can be read from a depth counter.