Recovered Water
Response
Sent: Wednesday, 25 March 2026 03:03 pm
Subject: Official Information Request - Recovered Water
I refer to your Official Information request of 10 March 2026 for information regarding Recovered Water.
Council would like to provide you, the below context regarding water quality and recovered water.
Water is often seen as the purest and most essential natural resource, yet the reality is more complex. All drinking or bathing water sources—whether drawn from rivers, lakes, streams, groundwater, or reservoirs—contain trace amounts of substances that could be harmful at certain levels. These include naturally occurring minerals, microorganisms, agricultural runoff, industrial residues, and byproducts of natural environmental processes. The presence of such pollutants does not automatically make water unsafe. Rather, it highlights the importance of regulation, monitoring, and appropriate treatment.
Natural water systems are dynamic and constantly interacting with their surroundings. As water moves through soil, rock, and ecosystems, it dissolves minerals and can pick up organic matter, bacteria, and chemicals. Even in remote or seemingly pristine environments, water can contain elements like arsenic, fluoride, or naturally occurring microbes. In urban and developed areas, human activity introduces additional contaminants such as pesticides, fertilizers, heavy metals, and trace pharmaceuticals.
To ensure community safety, health authorities around the world establish strict guidelines that define acceptable limits for these substances in drinking and other water sources. These limits are based on extensive scientific research and are designed to protect human and ecosystem health. Water treatment facilities play a crucial role by using processes such as filtration, disinfection, and chemical balancing to reduce contaminants to levels well within safety thresholds.
It is important to understand that “safe” does not mean “completely free of all contaminants.” Instead, it means that any substances present are at concentrations so low that they pose no significant risk to human and ecosystem health. Continuous testing and monitoring ensure that water quality remains within these defined limits, and regulatory frameworks require immediate action if standards are exceeded.
Public awareness is sometimes influenced by the idea that any detectable pollutant is dangerous. However, modern analytical techniques are capable of detecting substances at incredibly small concentrations—often parts per billion or even trillion. The mere detection of a substance does not equate to harm risk. Toxicity depends on dose, duration of exposure, and individual susceptibility.
In summary, all natural water sources contain a mixture of substances, some of which could be harmful at higher levels. Through careful management, treatment, and regulation, drinking water and water based systems ensure that these substances remain within safe limits. This balance allows communities to rely on their water supplies and environment with confidence, while acknowledging the complex and ever-changing nature of the environment.
For example, in Rotorua our drinking water is sourced from deep springs. The water before circulation is treated for bacteria and protozoa to ensure it is safe. Daily and weekly tests are undertaken to verify that this is indeed the case.
These drinking water sources are also tested at longer intervals (every few months or five years) to monitor trends of contaminants and that these trace elements remain within safe limits established by regulations.
These long-term trends monitoring cover trace elements such as, mercury, bromate, cyanide, chlorite sulphate, boron, barium, cadmium, lithium etc even uranium.
The trends monitoring cover also manmade pollutants such as heavy metals, hydrocarbons and organic compounds, nutrients, chemicals and toxins and a range of emerging contaminants.
The attached long-term testing monitoring indicates the over 700 natural or man-made contaminants that can be found in water sources and water environments that Council must ensure remain within specified safe limits. Please see:
Hill Laboratories Testing 6 December 2020 and 18 December 2020
Hill Laboratories Testing 20 September 2025 and 9 October 2025
This context is important because the recovered water sits within the same overall water quality framework.
Question:
A list of names of contaminants and pollutants (e.g. pathogens, pharmaceuticals etc ) that will not be removed from RLC's recovered water and why they won’t be removed? E.g. cost too much money, current tech doesn’t allow it, they pose no risk to the environment etc.
Answer:
Rotorua Lakes Council does not hold a complete list of all possible contaminants present in treated wastewater and Council does not hold a single consolidated document listing every parameter that has ever been analysed historically.
Municipal wastewater is a complex mixture derived from domestic water use, commercial activities, stormwater inflows, and trade waste discharges.
Contaminants from commercial activities and trade waste are in the first instance managed at source - the site’s trade processes, potential contaminants, and associated risks are assessed. Based on this assessment, specific pre-treatment requirements, cleaning and maintenance frequencies, and documented site management practices (via a Site Management Plan – SMP) are imposed to ensure the discharge remains low risk and acceptable. Regular site audits are undertaken to verify implementation and adherence to these pre-treatment systems and SMP requirements.
As a result, treated wastewater may contain thousands of individual chemical compounds, including naturally occurring substances, household chemicals, pharmaceuticals, industrial compounds, and transformation products formed during treatment processes.
It is therefore not practicable to maintain a complete list of all potential substances present. Like natural water sources, recovered water contains a wide range of constituents at varying concentrations, which does not in itself indicate harm, and it is therefore managed based on its intended use and the protection of the receiving environment.
Council does have information relating to wastewater quality within individual reports prepared for consent applications as well as compliance monitoring for general constituents:
- The treatment process includes ultra-filtration and UV treatment which will remove pathogens to levels that make it safe for returning to the environment and safe for managed non-potable reuse. Please see:
Rotorua Wastewater Treatment Plant Discharge Public Health Assessment April 2018
- Levels of indicators of groups of pharmaceuticals and emerging organic contaminants. Please see:
Presentation for the Recovered Water Working Group 21 November 2025
The reports find that following a mixing zone with 100x dilution there is no or minimal effect on receiving waters, and further reductions are anticipated in the environment, prior to reaching receiving waters.
- Please see:
The levels of general constituents are discussed within this.
Question:
Will Council's recovered water to be suitable for consumption by farm animals and freshwater aquatic taonga species?
Answer:
The recovered water is not intended for direct consumption by farm animals or aquatic species. Its use and discharge are managed so that environmental and human health outcomes are achieved at the point where the water interacts with land or natural water bodies.
The treatment process for recovered water includes advanced steps such as ultrafiltration and ultraviolet (UV) disinfection. The treated water is designed to meet applicable non-potable reuse guidelines, which are based on managing human health risks for specific uses (such as irrigation), rather than direct consumption.
While this level of treatment significantly reduces pathogens and improves overall water quality, recovered water may still contain nutrients, dissolved contaminants, and trace levels of emerging organic contaminants (EOCs). Monitoring undertaken to date indicates that, following discharge and mixing within the receiving environment (including dilution on the order of approximately 100:1), the levels of tested EOCs are expected to have minimal or no measurable ecological effect based on current science evidence.
For farm animals, there are guideline values for stock drinking water. The recovered water is not intended to be managed or supplied as a stock drinking water source, and its suitability for unrestricted animal access has not been specifically assessed.
For freshwater aquatic species, including taonga species, the relevant benchmarks are ecological protection guidelines. These guidelines are typically applied to the receiving environment rather than to treated water in isolation. Council’s approach is to ensure that, following treatment, discharge, and natural processes such as dilution and attenuation, the receiving environment is protected and meets applicable environmental safety level standards.
Question:
Will Council disclose (once it has decided on a discharge location) in its eventual consent application or accompanying AEE, that it only gave a 10 out of 100 weighting to environmental effects.
Answer:
For any option to be considered and to proceed to the stage 2 assessments and weightings, it must pass the requirement for Stage 1 of the process, which requires full compliance with national standards and environmental regulations.
