Illustrative concept, not a real site or discharge event.
The Christchurch City Council Trade Waste Bylaw 2025 came into force on 1 July 2025, replacing the 2015 version. It's the rulebook for anyone discharging trade waste, not domestic wastewater, to the city's wastewater network, and it's worth understanding properly if your business falls under it, rather than skimming the notice that arrives with your consent.
Who it applies to, and why it exists
The bylaw is made under the Local Government Act 2002, and its purpose, spelled out in clause 2, is broad: protect public health and the environment, protect the wastewater network and the people who work on it, ensure fair cost sharing between trade and domestic users, and encourage waste minimisation and water conservation along the way.
"Trade premises" is defined widely. It covers any premises used for an industrial or trade purpose, any site handling waste storage, treatment, or disposal, and any premises discharging something other than domestic wastewater, including land used for agricultural or horticultural purposes. Every trade waste discharge falls into one of four grades: permitted, conditional, tankered, or prohibited, and every occupier, even in the permitted category, must be registered with the council.
Part 4: flow metering
Clause 24 sets out when the council can require flow metering: when there's no reasonable relationship between metered water supply and the trade waste discharged, when the council won't approve an estimation method instead, or when the discharge is a significant share of the total flow the council receives. Where a meter is required, the consent holder owns it, and carries full responsibility for its supply, installation, reading, and maintenance, even though the council must approve its type and position.
The meter has to sit where the manufacturer's installation instructions say it should, in a position the council approves, and it has to stay accessible for reading and maintenance. Records must be available for the council to view at any time, and submitted at prescribed intervals in a council-approved format. If a meter is found to have drifted outside its accuracy tolerance, the council can adjust your fee calculation based on your previous readings, so a meter left unchecked isn't just a compliance risk, it can end up costing you money based on a guess rather than a fact.
Schedule 1A: what "permitted" actually looks like in numbers
Schedule 1A sets the physical and chemical characteristics a discharge must sit within to count as permitted, without needing a conditional consent. Some of the headline figures: the maximum instantaneous flow rate is 2.0 L/s, maximum annual volume is 1,245 m³ (roughly 3,400 litres a day averaged across the year), and temperature can't exceed 40°C. pH has to sit between 6.0 and 10.0 at all times.
On solids and grease, total suspended solids generally can't exceed 600 g/m³ (dropping to 100 g/m³ specifically for silts and sediments from construction activity), settleable solids are capped at 50 mL/L, and fat, oil and grease can't exceed 200 g/m³, with no free or floating layer allowed at all. BOD5 sits at a 600 g/m³ ceiling. Heavy metal limits are tight by comparison, mercury at just 0.005 g/m³, cadmium at 0.5 g/m³, and zinc at 10 g/m³, reflecting how little of these it takes to cause a problem downstream. Anything sitting outside these figures doesn't automatically mean you can't discharge, it just means you're in conditional territory, with the council setting specific limits for your site instead of relying on the standard schedule.
Calibration and verification aren't the same thing
Clause 24(5) requires the consent holder to arrange "in situ calibration" of their flow metering equipment on installation and at least annually, with the meter's accuracy required to sit within ±10%, and no more than ±5% deviation from the previous result. Worth flagging here: what's actually happening on site in that process is verification, not calibration, and the difference matters more than it might seem.
Calibration adjusts a device against a traceable reference standard, and it's done under controlled conditions, typically in an accredited lab, not out on your pipework. Verification checks a meter's accuracy against a calibrated reference without adjusting anything, and it's exactly what can be done in situ. When we verify a trade waste meter, we bring an IANZ-calibrated reference instrument to your site and compare its reading against your installed meter, recording a pass or fail to the required tolerance. The reference device is calibrated. What happens to your meter on the day is a verification. The bylaw's wording blurs the two, but the certificate you actually need is a verification certificate, and that's the service that satisfies this clause.
Fun fact: dental facilities get their own clause
Not many people would expect a trade waste bylaw to call out dentists by name, but clause 22 does exactly that. Every dental facility connected to the wastewater network needs a consent, and it must include an approved amalgam trapping maintenance and disposal system where relevant. It's one of only two specific activities named directly in the entire bylaw, alongside pre-treatment generally, and it exists because amalgam fillings contain mercury, and mercury is one of the tightest-limited heavy metals in the whole of Schedule 1A. A dental surgery isn't the first place most people picture when they think "industrial discharger," but under this bylaw, it absolutely is one.
Offences and penalties
Clause 36 is blunt about what happens if you breach the bylaw. Any consent holder, owner, or occupier who breaches it commits an offence, liable on conviction to a fine of up to $200,000, or an infringement notice under the Local Government Act. Breaches explicitly include failing to comply with any provision of the bylaw, breaching your specific consent conditions, ignoring a notice served on you, or simply failing to pay trade waste fees and charges by the due date. It's a wide net, and the size of the maximum fine reflects how seriously the council treats the wastewater network as shared infrastructure rather than a free disposal point.
Where NZ Flow Group fits in
If you hold a trade waste consent, the metering requirements in this bylaw are exactly where we work. We supply, install, and verify flow meters for industrial dischargers across Canterbury, and we can help with all three, whether you need a new meter specified and fitted, or an existing one verified annually to satisfy clause 24. We use IANZ-calibrated reference equipment to carry out the verification itself, so the certificate you get back is accepted by Christchurch City Council and every other Canterbury territorial authority.
If you're not sure whether your current meter, installation, or verification history actually meets what this bylaw requires, it's worth a conversation before the council's the one asking.
