The new group would evaluate options for additional long-term water sources or water storage in the district.
"The working party will look at ways we can maintain a comfortable margin between water supply and demand, now and in the future," he said.
"Our district is experiencing significant population growth, and we expect this to continue as transport connections to the south improve."
"We need to plan ahead to ensure we have enough water for our district's future residential, commercial and industrial needs."
After listening to public consultation during the Long Term Plan 2018-2038 process council would also carry out feasibility studies to connect some smaller communities to reticulated water supplies.
HDC adopted the terms of reference for the working party at its meeting on Wednesday 13 March.
Mr Clapperton said the working party will bring together representatives from HDC, Horizons Regional Council, MidCentral District Health Board, Iwi, Department of Conservation, Federated Farmers, relevant government departments, and community members.
The working party would will have an independent chair.
"The working party will have input into future Council decision-making on water supply issues, recommend commissioning technical reports as required, review the findings of any such reports, and make recommendations to Council."
He said establishing the Horowhenua Water Working Party was a commitment Council made to the community following feedback during public consultation on the Long Term Plan 2018-2028.
Horowhenua sourced drinking water from the Ōhau River, the Tokomaru River, the Mangaore Stream and bores in Foxton and Foxton Beach.
"The amount of water Council can take from these sources is limited by reasonable use targets under the Horizons One Plan and resource consents that aim to preserve the ecological health of the rivers," he said.
"Demand for water peaks during summer, when flows in our rivers are already low," Mr Clapperton said.
"Council already has an active water demand management plan to improve the efficiency of our water supply network, but it won't be enough by itself to maintain the level of service we want to deliver for our growing community.
"The Horowhenua Water Working Party will enable us to look at long-term options with the key stakeholders around the table."
The working party would be made up of Mayor Michael Feyen, Mr Clapperton, an HDC officer, a Horizon's officer, a MCDHB drinking water accessor, a district councillor, a regional councillor and representatives from Iwi, DOC, Federated Farmers, Weca, Tararua Growers and the relevant Government department.