Source Protection Zones

Project overview

T+T are technical experts in the development of source protection zones and risk assessments to help drinking water suppliers to understand their source water and the risks posed to groundwater and surface water supplies.

What is a Source Protection Zone?

A Source Protection Zone (SPZ) is the area around a groundwater well, spring or surface water intake where land use activities have the potential to affect the quality of the raw water. The shape and extent of the SPZ is determined by a variety of factors relating to the source. For instance, a groundwater SPZ is impacted by the land topography, geology, the amount of water being pumped, the type of aquifer, flow direction and travel times of groundwater. All of these factors help to determine how long it takes water to move through the aquifer to the well and how much land around the wellhead should be protected. A number of modelling approaches are used to delineate SPZs, ranging from very simple analytical models to complex transient numerical models.


Our specialists offer the full spectrum of capabilities relating to protection of source water, including:

  • Well and surface intake design to meet industry best practice for drinking water supplies
  • Development of SPZs for groundwater, surface water and conjunctive public drinking water supplies, using a range of modelling approaches
  • Development of GIS “catchment risk screening tools” using available data held by regional and district authorities
  • Catchment vulnerability mapping
  • Fate and transport modelling for contamination risk assessments
  • Full catchment risk assessments and technical reporting for groundwater, surface water and conjunctive sources
  • Specific inputs, such as catchment risk components and management controls, into water safety planning frameworks
  • Dye tracer testing to determine groundwater flow regimes
  • Expert witness in consent hearings, the District Court, Environment Court and High Court on groundwater-related issues.


We were technical advisors to the Hastings District Council during the Havelock North Campylobacter outbreak inquiry. As a result of our work during the Government Inquiry we now hold a technical advisory role within the current Government drinking water reform process and we are at the leading edge of defining groundwater source protection in New Zealand.

Our reputation for quality work includes:

  • Contamination investigation, dye tracer testing, fate and transport modelling, SPZ delineation, catchment risk assessment and expert witness during the Havelock North Government Inquiry
  • Technical advisory role on the independent Drinking- Water Advisory Committee setup by the New Zealand government to review the Drinking-Water Standards for New Zealand
  • Development of a bespoke GIS tool to screen and rank catchment risks in real-time, based on available GIS data in the Hawke’s Bay
  • Catchment sanitary inspections for Matamata-Piako District Council to support inputs into their Water Safety Planning process. This work included the development of SPZs for their well fields
  • Development of SPZs for groundwater and conjunctive drinking water supplies across the Hawke’s Bay (Napier and Hastings) using a number of modelling approaches
  • Public water well design and well field design optimization to meet drinking water protection objectives and industry best practice across the Hawke’s Bay. As well as Peer review of well decommissioning specifications for public water supply wells
  • Feasibility for new public water supply locations in the Waikato and Hawke’s Bay, including catchment risk assessments to identify any risks that comprise a potential supply
  • Well head sanitary inspections in the Waikato
  • Part of the working group to review the Environmental Standard for drilling of soil and rock NZS 4411:2001.