A Streamlined Methodology for Source Risk Management Plans – Enhancing Drinking Water Quality and Safety in New Zealand

Mar 21, 2024 | Drinking Water, Insights

It cannot be overstated the critical role that source water protection plays in maintaining public health. New Zealand’s drinking water reforms and regulations changes have been driven by waterborne disease outbreaks and contamination events, with the Havelock North standing out as a prime example. This tragedy has forced change across the country and prompted the government and the regulator to impose more stringent requirements, including the Water Services Act 2021 and proposed amendments to the National Environmental Standards for Sources of Human Drinking Water (NES-DW). These documents mandate more rigorous requirements for drinking water suppliers to assess and manage risks to their source waters, specifically the preparation of Source Water Risk Management Plans (SWRMPs).

In response to feedback on challenges faced by water suppliers, such as the boundaries of the catchments to consider, the type of information and potential hazards to look for, or questions such as whether neighbouring bore searches are providing useful information, our team formulated a streamlined methodology. This approach guides suppliers of all types and sizes through efficiently developing customised SWRMPs, tailored to the unique characteristics of their supply and surrounding risk context. This approach is thorough enough so no aspect is missed or overlooked but streamlined to only focus on the identification of relevant potential hazards and risks associated with the specific source waters. The key benefits are saving suppliers time and resources in unnecessary information request and research, while ensuring that no bespoke potential hazard or risk to the specific source waters are omitted.

The first step in developing a customised SWRMP is to categorise the type of source water used, whether surface water, groundwater or rainwater harvesting. Each source type has distinct considerations.

Step 2; with the source water classified, drinking water suppliers map out targeted Source Water Risk Management Areas (SWRMAs) surrounding their abstraction points based on specifications in the proposed NES-DW. Delineating SWRMAs enables suppliers to focus their risk assessment and control efforts within defined zones representing escalating proximity to the source water intake or abstraction point, and as shown in the figures below provided in the NES-DW Consultation Document.

  • SWRMA 1 covers the immediate vicinity around the intake where contaminants could potentially impact raw water quality within hours or days.
  • SWRMA 2 encompasses the contributing catchment area supplying water to the intake, requiring management of risks that could manifest within weeks or months.
  • SWRMA 3 represents the entire catchment and recharge zone for the source water, warranting surveillance for persistent contaminants that could eventually migrate from this wider area.
Figure 1: SWRMAs Ministry for the Environment 2022

Kia kaha ake te tiakina o ngā puna wai-inu / Improving the protection of drinking-water sources: Proposed amendments to the Resource Management (National Environmental Standards for Sources

Step 3; with SWRMAs mapped, drinking water suppliers gather and analyse publicly available information to build an understanding of potential hazards and contaminating activities within each zone relevant to their source water type. Useful data includes regional and district council resources related to land use, resource consents, water quality monitoring data, contaminated site listings, and hydrogeological maps.

It is worthwhile noting that while rainwater harvesting doesn’t have defined SWRMAs, it is still vital that water suppliers address potential hazards relating to source water management, using the same resources and information available.

Step 4; Key findings from the source water risk assessment are then integrated into the supplier’s broader Water Safety Plan through risk characterisation and tailored preventive measures, treatment upgrades, enhanced monitoring, incident response plans, and contingency plans, as shown on the Water Safety Plan Risk Table snippet below. This ensures suppliers proactively implement appropriate control measures while preparing effective responses if the water supply is at risk.

Figure 2: Example of incorporating groundwater source hazards into Water Safety Plan Risk Table, where both water quality and quantity issues are addressed, source GWE Consulting Engineers.

Simple flowcharts, like the example provided below can also serve as practical tools for responding to transgressions and provides clear guidelines on procedures to follow in these situations.

Figure 3: Transgression Response Flowchart, source GWE Consulting Engineers.

SWRMPs must be living documents, requiring regular updates and continuous review to ensure they remain relevant to changing context and evolving risks. Updates through two-way communication channels between regional councils and water suppliers enables prompt identification of changing or new emerging risks within water supply catchments. In addition, by keeping a close eye on the State of Environmental Monitoring for managing trends on water quality, suppliers can make informed decisions and modifications to their risk management strategies.

It is important to highlight the importance of integrating SWRMPs into the broader framework of Water Safety Plans to ensure that all aspects of the water supply system are considered and addressed adequately. Moreover, it is part of all suppliers’ duty of care under the Water Services Act 2021 to carry out a certain level of source water risk assessment, regardless of their sizes; even when adopting alternative compliance pathways such as Acceptable Solutions.

In summary, this streamlined methodology provides a roadmap for efficiently developing customised SWRMPs that form the foundation of drinking water safety and proactive risk management programs for all water supplies, regardless of their types, sizes, compliance level or registration status, benefiting all New Zealanders who rely on access to safe drinking water every day.

Maria Johnson, Water Sector Lead at GWE Consulting Engineers Ltd

In her career in NZ, Maria is dedicated to ensuring drinking water meets the highest standards across a range of supply types and sizes, aligning with the transformative water reform.