Trade Waste
What is excess wastewater?
Property owners pay a targeted rate for wastewater (sewage) which covers the cost of transporting and treating the wastewater before it’s returned to the environment. This fee is based on the number of toilets (also called “pans”) on the property, not how much water is used. You’ll see it on your property rates bill as a “Sewage Disposal Charge, X number of pans” (where X is the number of connected toilets on your property). Certain properties may have to pay an excess wastewater charge if they use more water than their targeted sewage rate covers for the quarter.
What properties are subject to excess wastewater charges?
Excess wastewater charges apply to non-residential properties and geothermal discharges discharging to the Rotorua sewer network.
When is excess wastewater calculated and charged?
Water use at your property is measured every three months, unless otherwise specified in your Trade Waste consent. If the cost to treat the wastewater from your water use is higher than what you've already paid through your fixed Sewage Disposal Charge, you'll be charged an excess wastewater fee for the extra amount. This happens quarterly, in line with your water meter readings and water bill.
What is the measurement for wastewater?
Wastewater discharge volume is measured in cubic metres (m3 ). One cubic metre is 1,000 litres.
How is the discharge volume of wastewater determined?
The amount of wastewater your property creates is based on how much water your property uses, as measured by your water meter. For most industry types it’s assumed that 95% of the water coming into the property ends up as wastewater. Some large commercial properties have their wastewater directly measured. This is more difficult and costly than water metering and the user (rather than the property owner) pays this cost, which includes metering, sampling, and analysis. These details are included in the user’s Trade Waste consent.
How is excess wastewater calculated?
To calculate your excess wastewater charge:
- The total volume of wastewater generated by your property is determined (at 95% of your total water use).
- That amount is then multiplied by the cost to treat each cubic metre of wastewater (this treatment charge can be found in the list of fees and charges). Excess Wastewater: frequently asked questions Version: 2, Version Date: 04/12/2025 Document Set ID: 21927410
- The fixed Sewage Disposal Charge you’ve already paid in your property rates is then subtracted from this value.
- The remaining is your excess wastewater charge.
Who is issued the excess wastewater invoice?
The property owner is responsible and liable for all water services provided to the property, which includes wastewater. The excess wastewater invoice is issued to the water service debtor, i.e. the same debtor who pays the water rates.
If I get an excess wastewater charge once, will I get them every quarter?
Not necessarily, it depends on usage. If your water use was unusually high this quarter (for example, due to a one-off event or a leak), you might not get charged again in the future. But if your higher water use continues, you may start getting an excess wastewater charge every quarter.
I received an excess wastewater charge because of a water leak, what should I do?
If you had an excessive water leak on your property that was promptly fixed you can apply for a water rates reassessment. To do this, you’ll need to show proof that the leak has been repaired, and your water use is back to normal. At the same time as the water reassessment please indicate that your excess wastewater charges need to be reviewed. For more information visit the Water Metering page.
What if not all the water we use goes to the sewer?
We understand that not all water used on a property ends up as wastewater. Additional water may leave or enter the property (for example in products) or lost in other ways (for example by irrigation). In Rotorua the default discharge factor for water meters is 95% to sewer. This assumes that 5% of the water supplied to your property does not go down the drain. This is in line with the approach taken by other councils across New Zealand. View a list of industry variations to this default factor on this page.
If you think your wastewater is much less than the water you have been supplied, you can talk to a Trade Waste Officer about installing a wastewater meter to measure it directly. Details of the installation, maintenance, measurements, and charging will be included in your Trade Waste consent.
What if I use other water sources for things that don’t create wastewater, like watering gardens or dust control?
Using alternative water sources will help you save money on your water bills and help reduce community reliance on council water supplies. Examples include rainwater, groundwater (from a bore), river water (if you have a consent), recycled treated wastewater, treated greywater, captured condensate (from air systems), sump water, etc.
If you use an alternative source of water which is then discharged to sewer, you will need to meter this supply. You can talk about your options with a Trade Waste Officer.
