Marsh plant systems have been shown so far as we are aware for the first time to decontaminate water polluted with a pesticide, specifically the herbicide, atrazine. The mechanism of decontamination has also been shown to be biologically-based - specifically microbially-based - and to reside in the rhizosphere. The type of microbe involved in the decontamination of atrazine is presently unknown. The removal of pesticides by the marsh plant systems is a simple, inexpensive clean technology which could be transferred to, for example, individual farms where the pesticide pollutants would be treated at source.