The Top Things You Need to Know About the 2025 DWQAR Level 3 Changes

New Source Water Classes and Viral Treatment Requirements

Currently, the S3 rules require classification of the source water into category 1 to 4. This will now change to category A to D. It’s not just changing numbers to letters, it’s introducing a completely new class A.

To be classified as a class A source, the source must meet the following criteria:

• Groundwater abstracted from a depth of greater than 30 metres below ground level (with depth measured from ground level to the top of the upper most screen), and abstracted via a sanitary bore head.
• No E. coli or total coliforms have been detected from monitoring over the previous three years with 12 samples taken per year evenly spaced over the year.
• An enteric viral indicator monitoring programme, including a written report prepared by an independent suitably qualified and experienced person, demonstrates that a health-outcome target of 1 enteric viral infection/10,000 people/year can be achieved and maintained for the supply.

The proposed update also provides interim status for Class A and B if there is a lack of monitoring data. Interim status can be held for up to 2 years.

Viral Treatment Rules

The proposed update includes viral treatment requirements. The viral treatment requirements have been combined with the bacterial treatment requirements and from a practical point of view there is no difference as there are no additional treatment processes required.

The proposed viral treatment rules do not follow a log reduction-based approach and a blanket treatment requirement has been set (e.g. 15 min.mg/L for chlorination, or 40 mJ/cm² for UV disinfection).

All Sources Must be Chlorinated

What may seem contradictory to the new Class A, all treated water must be chlorinated. This is a requirement from the Water Services Act and is intended to provide a chlorine residual in the network.

As Class A sources do not require a bacteria/virus barrier, this practically means that Class A sources do not need to demonstrate a sufficient C.t value. Class B to D are required to demonstrate a sufficient C.t value, this is no change to the current rules.

Certain Treatment Options Have Been Removed

The rules update proposes to remove the following processes from being able to demonstrate compliance:

• Bacteria/virus rules
  • Chlorine dioxide
• Protozoa rules
  • Coagulation without filtration [0.5-log]
  • Coagulation with direct filtration [2.5-3.5-log]: 3.0-log and 3.5-log 
  • Second stage filtration [0.5-log]
  • Slow sand filtration [2.5-log]

Please note that coagulation with direct filtration can still be used to demonstrate protozoal compliance but can only award 2.5-log credit.

The removed processes will affect some supplies necessitating treatment process upgrades to meet the protozoal log credit requirements. 

Chemicals Now Require a Certificate of Analysis or a Certificate of Compliance

All chemicals added to a drinking water supply now require a certificate of analysis or a certificate of compliance. This certificate seeks to ensure any chemical added has a demonstrable purity and there is certainty about what is being added to the supply. 

Another requirement is for water suppliers to prepare a schedule of all chemicals added in the process and monitor for the chemicals dosed and formed in the process (MAV).

Speak to Lutra about how we can assist with storing these in ID.

Updated Rules For Recycle Streams

Recycling waste streams to the head of the plant can currently be done not exceeding 10% of the plant inflow. It is proposed that the recycle stream (measured as the 30-minute rolling average recycle rate) can exceed 10% for the following time limits:

• >10% for up to 5% of the compliance period
• >15% for up to 15 minutes

This can be done as long as the downstream water quality is not detrimentally impacted. At the moment it is not defined what detrimentally impacted actually means and whether there will be a rule around this with clear limits.

Updated Requirements on Cyanobacteria/Toxin Risk

Any class C or D source must be assessed for cyanobacteria risk (low, medium or high) for both benthic and planktonic species (separately). This must be done by a qualified and experienced person and must also provide a risk analysis on when it is likely to be present.

If the cyanobacteria risk is classed as medium or high then the relevant species (benthic and/or planktonic) must be monitored and treated using a cyanotoxin removal process.

Final Thoughts

The proposed changes to the level 3 rules will bring some changes and some supplies will have to undertake upgrades to meet the proposed rules. From a legal perspective, many of the rules were not enforceable, the proposed format change seeks to improve this by making everything a rule. 

The proposed changes are significant, and this list is only what I believe are the most noteworthy ones. The Pareto principle (The Pareto principle, or the 80/20 rule, states that roughly 80% of outcomes result from 20% of causes) applies to this list and the catch is in the detail. There have been many (smaller) changes, especially around monitoring rules, that will have impact and which I have not covered and that are aimed at simplifying the rules. To name a couple: 

Additionally, there is an increased requirement to have plans in place, e.g. chemicals plan, updated cyanobacteria/toxin management plans, water storage management plan etc. The rules do not dictate what content the plans must have in place, and it is to be seen whether guidance will be provided.

I encourage you to take your time to read through the proposed changes, and provide any feedback to Taumata Arowai. If you have any questions on how this may affect your supply, we’re happy to have a chat!