Sewage treatment standards

The Resource Management (Marine Pollution) Regulations 1998 (the Regulations) outline three treatment standards that specify where sewage can be discharged, in order to control pollution of the sea from sewage:

• Grade A treated sewage
• Grade B treated sewage
• untreated sewage.

Grade A treated sewage

Systems that treat wastewater to the Grade A standard, outlined in Schedule 6 of the Regulations, are generally found on ships.  

These systems often include a bacterial breakdown and disinfection stage prior to the discharge of treated wastewater.

A list of certified systems is contained in Schedule 5 of the the Regulations.

Ships equipped with a Grade A treatment system, that is operated and maintained according to the manufacturer's specifications, must not discharge treated sewage in the following areas:

• within 100 metres of a marine farm
• within the internal waters of Fiordland.

Grade B treated sewage

Boat operators can use a Grade B sewage treatment system, as listed in Schedule 7 of the Regulations, to reduce the impact of their wastewater discharges on the marine environment.

The treatment process in Grade B systems usually involves mechanical breakdown and disinfection, before discharge.

Treatment systems must be operated and maintained to the manufacturer’s specifications to be effective. Treated sewage must not be discharged:

• within 500 metres of a marine farm or a mataitai (traditional food collection) reserve
• within area’s prohibited under rules in a Regional Coastal Plan.

Untreated sewage

Sewage that is discharged in an untreated form is a greater threat to the marine environment and its users than wastewater that is treated. Therefore, the Regulations specify more restrictions to control the discharge of untreated sewage.

Discharges must not occur:

• within 500 metres from land (mean high water spring)
• in water less than 5 metres deep
• within 500 metres from a marine farm or mataitai (traditional food collection) reserve
• within 200 metres of a marine reserve
• within areas prohibited under rules in a Regional Coastal Plan.

The following measures give boat owners/operators without treatment systems greater flexibility to work within sewage discharge requirements:

• encouraging crew to use shore-based toilets before you sail
• installing a holding tank so that on board toilets can be used within restricted areas
• fitting deck valves so holding tanks can be pumped out at marina-based reception facilities
• disposing of waste from portable toilets in land-based reception facilities, particularly if a chemical deodorant has been used
• enquiring whether pump-out facilities are available and operational at your marina before you sail.