The current use of the land by the Jury Hill Gliding Club and recreational access to the rivers would not be affected.
Mrs Staples said the Government had made it clear that local bodies must drastically reduce or stop treated waste water from being discharged directly into streams and rivers. Greytown effluent discharges into the Papawai Stream which flows into the Ruamahanga River.
"We see this purchase as a major step for South Wairarapa's plans to comply," she said.
"Improved arrangements for the treatment of waste water in South Wairarapa have long been part of our long-term planning and this purchase marks a major step forward."
Wastewater treatment and disposal is one of the council's key issues, along with water supply and the strengthening of Martinborough Town Hall.