The socio-economic and ecological value of wetland ecosystems is widely acknowledged. As a result, considerable efforts are now being made to rehabilitate and in some cases recreate wetlands throughout Europe. An option for the restoration of worked-out peat pits is to establish reed beds. Ham Wall, located in Somerset in the UK, comprises reed bed and a mosaic of other wetland habitats that has been constructed as a wildlife area. Since 1996, water chemistry has been monitored for a 16.5 ha wetland compartment planted with reeds in July 1995. Water is pumped into the reed bed from Ham Wall Rhyne, a drainage ditch supplied with nutrient-rich runoff from the surrounding agricultural land. The principal objectives of the research described in this paper were to investigate differences in the chemistry of water from different locations in the vicinity of the wetland and to evaluate seasonal changes and trends in water quality as the reeds matured. The results obtained provide insight into the biogeochemical functioning of the wetland system.