NZ Water Metering Compliance

Regulatory Framework

Water metering in New Zealand is governed by three key standards:

• Resource Management (Measurement and Reporting of Water Takes) Regulations 2010/2020 — Defines water year (1 July – 30 June), reporting obligations, and accuracy requirements.
• National Environmental Monitoring Standards (NEMS) — National Quality Code Schema v3.0.0 — The quality coding framework applied to all environmental data, including water meter readings.
• NEMS Water Meter Data Standard — Sector-specific requirements for electronic water meter data: recording intervals, verification, and submission formats.

Key Requirements

NEMS Quality Codes

Every data point carries a quality code from the NEMS National Quality Code Schema v3.0.0. Codes QC 400–600 reflect measured data quality; codes QC 0–300 are categorisation mechanisms and do not rate quality.

Note: The “Poor” label was removed in NEMS v3.0.0. QC 400 is now “Compromised”. QC 0 (Non Verified) was added in v3.0.0 for raw data prior to quality assessment.

Quality Code Assignment

Based on NEMS v3.0.0 Figure 2 — Generic Quality Flowchart. Each data point is assessed top-down; the first YES determines its quality code.

Supplementary Child Codes

Per NEMS v3.0.0 Section 5, child codes are allocated in-house to provide supplementary quality detail. Format: Parent-Child (e.g., 600-010). When submitting to councils, the parent code is the primary identifier; child codes provide optional additional context.

QC Caps Reference

Certain conditions cap the maximum achievable quality code, regardless of other factors.

Ground Truth Methodology

All consent compliance totals use ground truth calculations — the only method that provides 100% accurate volume totals from pulse-counter telemetry.

Why Ground Truth?

Water meters transmit cumulative pulse counter values at 15-minute intervals. Pre-aggregated data (e.g., “volume per bucket”) can lose pulses that fall on bucket boundaries. The ground truth formula avoids this entirely by using the raw counter extremes over any period.

Formula

-- Ground truth: 100% accurate for any time period
SELECT MAX(gpio_counter_1) - MIN(gpio_counter_1)
FROM telemetry
WHERE device_id = :device_id
  AND time >= :period_start
  AND time <= :period_end

This returns the exact number of pulses recorded, regardless of how they align with reporting intervals. Each pulse represents a fixed volume (typically 1 litre per pulse).

When to Use What

Data Integrity

Our data integrity approach ensures that original measurements remain trustworthy and auditable.

• Append-only telemetry — Raw telemetry data is append-only. Original measurement values are preserved as received from field devices.
• Manual readings preserved — Manual meter readings are stored alongside telemetry data with their own quality codes and are never overwritten.
• Corrections via audit trail — When data corrections are necessary, they are tracked through an auditable workflow. Original values are retained.
• Calibration logging — When meter calibration factors are adjusted (e.g., after a verification test reveals offset), both the before and after values are recorded.
• Quality code metadata — Quality code changes are the one permitted metadata update on existing records. The measurement data itself is not modified — only the quality assessment of that data.

Meter Verification

All water meters must be verified to ensure measurement accuracy, as required by the Resource Management (Measurement and Reporting of Water Takes) Regulations 2010.

Alert Timeline

Council Reporting

The portal generates council-ready reports in the format required by regional councils under the Resource Management Regulations.

NEMS Version Tracking

Per NEMS v3.0.0 Section 7, systems must track which schema version their quality codes conform to.

Key Changes in v3.0.0

• QC 0 (Non Verified) added — New code for raw data prior to quality assessment. All incoming telemetry starts at QC 0.
• “Poor” label removed — QC 400 is now “Compromised”, not “Poor”.
• Version tracking required — Systems must record which NEMS schema version is in use (Section 7).
• Child coding formalised — Section 5 provides the framework for supplementary quality codes allocated by data providers.