Verum Group is putting their experience in passive water treatment systems toward a new target, the removal of nitrate from agricultural water. This research uses a system to remove nitrate from tile drain water on a participating farm in the Waikirikiri-Selwyn River catchment. We are trialling two bioreactor systems, a more traditional woodchip bioreactor, and a "enhanced passive treatment system". By providing additional nutrients into the reactor, we create a favourable environment for the bacteria to flourish and reduce the nitrate to nitrogen.