Drinking Water Quality Assurance Rules

Yes, in general Council is supportive of the proposed Quality Assurance Rules. In some areas, though, there is a level of prescription that does not necessarily align with the objective of Taumata Arowai of encouraging water suppliers towards taking greater responsibility for proactively managing their supplies using a risk management approach with multiple barriers.

No comment – planned temporary drinking water supplies not used.

Yes. The modules are well set out and understandable. The ability to select a more complex treatment module is supported, though some clarity is required regarding multiple treatment steps.

Source Rules – Intermittently used sources
Section 3 states that compliance only needs to be demonstrated “…for the time that the plant is operating to fill the storage tank.”
Some sources (particular for our smaller banks peninsula supplies where summer demand increases) only operate for part of the year.
S2 rules require monthly monitoring for several parameters.
S3 rules weekly and monthly monitoring.
Clarification is sought with respect to sources that are only used intermittently for weekly and monthly monitoring. If the source is not used, for example, for the past week or month, then is sampling required?

Trickle Feed Supplies and Backflow
F1 prescribes a single solution for backflow for Trickle Feed or ‘restricted’ supplies involving private tanks, which are technically beyond the point of supply. Solutions to protect against backflow can also be provided at the property boundary. A backflow device at the property boundary is often a more practical solution but F1 currently precludes this as an option.
Council advocates for their Trickle Feed water supplies serving less than 500 people to have the option of meeting D2 rule D2.7. Council’s experience is that this adequately manages the risks of backflow.

Calibration
G5, G8. Definitions of calibration and verification have not been provided. These terms have a history of being misinterpreted (along with terms such as standardisation and validation).
Full calibration of some instruments, where actual adjustments are made to the measurement function, is a highly technical procedure that some manufacturers require is only performed by their own technicians. An example of this is UVT analysers. Requiring such full calibrations to occur monthly for all instruments used in compliance measurement is impractical and overly onerous, potentially leading to increased risks and unnecessary expense.
Council seeks definitions of calibration and related activities and recommends that appropriate frequencies for activities are assigned to each parameter (turbidity, chlorine, UVT etc) and the type of instrument (portable, on line) as appropriate.

Continuous monitoring of source water, particularly at intakes, for parameters such as turbidity and pH (where a combined source water reading at the treatment plant may also be undertaken) are not necessary for treated water compliance. These instruments are used to establish trend analyses and forewarn plant operators of changing conditions. It is considered that calibration of these at a reduced frequency does not present a compliance risk.

Sample Collection/Delivery Temperatures
G4 requires that all micro-biological samples are delivered to the laboratory within 24 hours of the sample being collected and must be transported at a temperature of less than 6 degrees Celsius. The IANZ accredited CCC laboratory undertake the majority of the sample collection for CCC owned drinking water supplies. The staff report that it is common to receive compliance samples at the laboratory with temperatures that exceed 6 °C but are less than 10 °C. Staff have trialled the use portable refrigerators in the past but found that these were more likely to result in freezing of samples. The concern is that the change in requirements to less than 6 °C will result in samples being invalid for compliance testing, either by exceeding the temperature limit, or by being frozen in an attempt not to exceed it.

The current DWSNZ requirement is that “samples must not be frozen and must arrive at the laboratory at a temperature not higher than 10°C or not higher than the temperature of the water being sampled”. The current requirement is in line with section 9060 B. b. of “APHA, Standard Methods for the Examination of Water and Wastewater (23rd Edition)”, which recommends to “keep samples cold but unfrozen (<10°C) during transport to the laboratory.”

In addition, the current recommendation in the Drinking Water Standards for NZ (2018) where samples which exceed 10 °C, can still be accepted if they don’t exceed the water temperature measured at the time of sampling, is useful, as samples delivered to the laboratory within an hour of collection haven’t yet had time to cool to less than or equal to 10 °C.

Our preference is to retain the current temperature rule for E. coli (DWSNZ 4.2.6.2), and extend it to other microbes, where appropriate.

Reporting Time Frames
G1 and G2: Council is in agreement with more frequent reporting timeframes but would seek a 15-day reporting time during the initial transition period while new reporting mechanisms are adopted and refined.

Storage of Continuous Data
G9 requires that for all continuous monitoring equipment, the separation between data records must be no more than 1 minute. With the increased requirements for continuous monitoring for source water and within the distribution there will be an increase in the amount of data. We request clarification regarding whether the accepted practice of dead-banding can be used for data storage. Dead-banding can provide more accurate data collection during times of change whereas polling may miss some peaks.

Cyanobacteria
S2.5 – Categorisation of cyanobacteria risk. Additional information is sought to confirm categorisation of cyanobacteria risk this. Generally, we would suggest a surface source water should be considered ‘high’ risk if previously algae have been found at that site or found within the same river system.

Source monitoring – Multiple sources
Section 3 clearly states that “Where a water supply abstracts water from multiple sources, the rules apply to each source”. But some ambiguity is introduced in Rules S2.8, the Note 20 to Table 14 and Note 24 to Table 15. Please clarify the sampling requirements for individual sources for S2 and S3 rules and clearly define which parameters may be sampled prior to treatment from locations that combine sources and which parameters must be taken from individual sources.

T2 Rules and Multiple Treatment Steps
The T2 rules section is quite prescriptive regarding the treatment options that are available for compliance. The filtration choices state that membrane filtration is an option but then do not give compliance criteria for this. A membrane plant would usually give a log credit of 4 and so including both a primary disinfection and secondary disinfection step (UV to 40mJ/cm and chlorine) would likely be overly engineering the treatment plant. Council is planning to install two membrane filtration plants (one a new supply and one an upgrade) for small supplies. Plans, based on current compliance, would require chlorination in addition to the membranes, but T2 rules would also require UV disinfection, which is over engineering and additional expense for a small supply, unnecessarily increasing capital and operational costs for these communities.

Council has a small supply, which was compliant for the 20/21 year, where the treatment used (Slow Sand Filter) is only available as a T3 option. This plant also has a UV disinfection step and will need to introduce secondary chlorination. The UV plants do not measure UVT continuously so they currently do not meet proposed T3 rules but would meet T2. Council request clarification regarding the situation when there are several treatment steps, and one needs to be selected at a higher module, as to whether other treatment steps can be operated compliantly using T2 rules.
It is understood that small privately run supplies might have requested a more prescriptive regime and the Acceptable Solutions option should be tailored towards these supplies. There are many councils successfully running small supplies using a range of treatment options not just those currently available under T2. Alternatively, a mixture of T2 or T3 rules could be applied for different treatment steps.

If a mixture of T2 and T3 rules could be adopted then further clarification is also sought as to whether the chemical and cyanotoxin rules would be adopted based on the size of the supply (T2) or would be required to follow T3 rules because one treatment step adopted followed T3.

pH + FAC range rather than FACE
D2 rules (Table 13) have the approach that compliance limits for the distribution zone are based on FAC and pH (rather than FACE). With respect to the efficacy of the chlorine residual, the requirement should be on demonstrating FACE. Having the specified range for pH of 6.5 to 8 within Table 13 creates confusion with the aesthetic value range that is specified for pH in the Aesthetic Values consultation document. The lower component of the FAC range means that an aesthetic component is incorporated within the water safety compliance limit. The compliance limit (for water safety) should either be an FACE limit or should just specify pH <8.0.

Daily Sampling Requirement FAC/pH
General rules – G5 talks re equipment used in grab samples taken to demonstrate compliance being calibrated, so the assumption is made that daily FAC and pH monitoring requirements can be completed using appropriately calibrated field equipment, this does allow for a wider pool of people able to undertake the monitoring. The use of calibrated field equipment is strongly supported by Council. However, for isolated small supplies, the requirement for daily monitoring will be a significant burden on staff (T2 and D2). Using field equipment would allow appropriately qualified treatment and reticulation staff to also undertake the monitoring, but daily will still be a significant burden for small supplies.
Change is sought to monitoring requirements of T2 and D2 Table 13 – daily FAC and pH. This is sought considering that the D3 rules require only daily monitoring of FAC and pH up to a population of 20,000, so allowing less than daily monitoring for populations of between 50 and 500 would be appropriate. We suggest a regime of 5 samples per week for FAC and pH with at least one Saturday or Sunday sampled each week.
Clarification is also sought as to any specific requirements around the collection and management of the dataset from field analyses.

Class 1 water
Class 1 water determination relies on the monitoring of E.coli and total coliforms. For Christchurch source water sampling, the current practice includes taking samples at the outlet of a pump station from sampling points on pumps. The sample will therefore comprise a combination of whichever sources are operating at the time (with up to six bores serving any one pump station). This means that there is often not a clear record of three years monitoring for individual bores.
To enable better alignment with the draft National Environmental Standard (NES) for Sources of Human Drinking Water, evidence regarding one year travel times should be able to be taken into account (this is the default source water risk management area (SWRMA) to provide microbiological protection, including protozoa). Additionally Council suggests it would be appropriate to incorporate other monitoring established and used in the current DWS. This would include Aging of the water, where multiple occurrences or aging results clearly show that a bore is well over 1 year (to allow for variation that is now accepted as possible throughout the year when ground flow conditions and recharge might vary) and modelling results.

In addition, the Assurance Rules have mixed the terms – ‘Class 1’ and ‘Category 1’ – do they essentially mean the same – clarify and use a single term. M

Interim Class 1
Interim Class 1 requires “…daily monitoring for a month, and then weekly until three years of data has accrued…” It is not clear if this means monitoring for three years or until the equivalent amount of data that Class 1 water requires is accumulated – ie monthly monitoring for three years (daily for a month = approx 30 samples plus a further 6 samples to give the equivalent of 3 years of monthly sampling)? Otherwise continuing to sample weekly for 3 years would give far more than the original 3 years of monthly monitoring for Class 1. Council seeks clarification of the Interim Class 1 requirement: Support Intensive (daily) monitoring for a month and then monthly monitoring for 6 months and the water is then considered Class 1.

Sanitary Bore head requirements
Council supports sanitary bore heads for all bores/wells, which through their penetration of aquitards present a potential risk of contamination to aquifers.

Source Monitoring S3 (Tables 14 and 15)
In addition to comments regarding S2 monitoring. The terms ‘abstraction point’ point and ‘source’ have separate definitions in the Water Services Act (WSA) but in the draft rules, they seem to have been used interchangeably. Abstraction points from different locations along a river or from different depths within a dam can expect to have quite different water quality parameters. However, abstraction points from a confined aquifer within a relatively restricted area (for example aquifers 1,2,3,4 and 5 under Christchurch) would not be expected to have significant variation in the parameters required to be monitored in Tables 14 and 15. The WSA appears to concur with this by requiring the inclusion of each abstraction point in the registration information only “if applicable”. Council does not agree with the stance of treating each abstraction point within a confined aquifer as an individual source of raw water and does not believe this was the intention of the WSA.

Changes to UV Treatment
Council support the assurance rules allowing up to 4 protozoa log credit for UV treatment and the increase in the acceptable turbidity up to 5.0 NTU. This is more consistent with the validated performance of certified UV units.

Monitoring of Chemicals used in the treatment processes
This is supported in general but it is important to understand how chemicals behave – often ions, metabolites or simply changes in pH would signal a carry over. Will also require careful timing when chemicals have specific timed use rather than routine use (eg. Cleaning membranes). Clarification is sought for the mechanism of agreeing on the requirements for monitoring of additional chemicals used that are not currently included in Table 30.

Continuous Monitoring of FAC/pH in the Distribution Zone
The requirement for continuous monitoring of FAC and pH in large distribution zones is a significant new requirement. Council agrees on the importance of continuous monitoring as part of good distribution management and we are currently piloting real time pressure and acoustic sensors and smart meters in one of our Christchurch city distribution zones. A number of decisions have yet to be made before definitive resourcing to meet compliance can be made; see additional comments in the ‘Transitional Time’ question below.

D3.26 Continuous monitoring (FAC, pH)
This is required in two locations:
1) at supply point – eg reservoir or bulk supply point and
2) Outer extent of distribution where might expect deterioration.
Point 1) is essentially the same point as Table 16 T3 monitoring post treated water storage/contact tank. This is essentially written for a treatment plant with a contact tank which then provides water to a separate reservoir, which is not necessarily present.
In addition, there may be several reservoirs within a large supply.
Council seek clarification as to whether sampling at the TP post treatment can be considered as the ‘supply point’ and whether all reservoirs require continuous monitoring.

D3.2 Backflow
This requires periodic surveys to determine medium and high-risk sites. Council has installed backflow devices suitable for high risk activities at all sites where our district plan would permit such high risk activities to be undertaken, regardless of the current use of those sites. These devices are included in our backflow register and will be regularly serviced and tested, as required. Further surveying for high risk activities is therefore no longer required unless the district plan makes changes to land uses that allow for new properties with high activities. Council would seek a change to the wording that allows for this situation, that is where the highest level of risk has already been addressed.

D3.6 Use of Hydrants
This rule prevents access to hydrants through use of a standpipe; it is not permitted except by FENZ, other emergency services, the water supplier or authorised contractors where is reasonably necessary to access the network for the operator of the drinking water supply. Council is supportive of this rule and we are moving towards dedicated points for water tankers to access water. This is a reasonably large project and won’t be fully in place by mid-November 2022 – see comment in Transitional Time sections.

Transitional Provisions
Christchurch has concerns regarding the transition time required to adopt to the proposed rules. Council has kept itself abreast of developments and have taken opportunities to actively participate where possible. The revised Drinking Water Standards and associated Quality Assurance rules and other documents have been touted as reformatting and making more understandable (and that achievement is acknowledged) but they also contain considerable changes for Council’s supplies. The outcome of the consultation and the final Quality Assurance Rules will not be available for some time. It is noted that there have been significant changes in requirements around continuous monitoring that only appeared in the consultation version of the Assurance Rules, not the exposure drafts. The transitional period is also likely to be affected by the significant disruption of global supply chains that COVID 19 is causing with the lead in period for ordering equipment now sitting at months rather than weeks.

Christchurch will apply for an exemption for residual disinfection in its urban Christchurch supplies and we do not know how long a decision on that application will take.

The continuation of criteria 1 (E.coli and total coliform testing for treatment plant compliance) during the Transitional Period will allow on-going compliance to be demonstrated through this period.

To complete the project to construct dedicated stations where water can be obtained by tankers etc. is expected to take approximately 2 years. In the meantime, access to water through hydrants is only permitted by authorised persons using an approved standpipe. Standpipes are hired from a recognised supplier who requires their return every three months for an integrity and backflow check.

A realistic transitional timeframe should be set by the water supplier once requirements are definitive and incorporated into their risk management plan with risks from non-compliance being actively managed in the meantime.