This proposal aims to develop a novel photo-electro-bio-catalytic (PEBCAT) reactor for the treatment of groundwater contaminated with nitrates, persistent organic pollutants, and chlorine resistant microorganisms. The proposed tandem reactor electrochemically links the photo catalytic destruction of organic pollutants and microorganisms, to the electro-bio-catalytic denitrification of water. A major proportion of the EC's drinking water is derived from groundwater sources and this project can make a substantial contribution to alleviating the pressures on our limited resources by allowing drinking water abstraction from contaminated sources. The consortium includes experts from photo electrochemistry, biotechnology, sensor technology, engineering and chemical engineering. The principal objective is to develop a pilot scale PEBCAT Reactor capable of treating real water at an affordable cost.