Project Little Oneroa

To restore the Little Oneroa Stream so that it is safe for human contact and recreation and meets our environmental, social & cultural values.

Little Oneroa Stream - What's happening here?

The Waiheke Community has been working to learn more about why the stream is polluted and what we can do to change that. Here is what we have found.

The Lagoon is currently unsafe for human recreational contact.

The main sources of contamination are

  • Poorly performing on-site waste water systems
  • Bird and dog faeces

Pollution levels fluctuate due to weather, tides & sand blocking the lagoons from flow towards the ocean.

These are natural occurrences.


There are 4 things we can all be doing to help

  • Don’t feed the ducks

Ducks breed to the amount of food available. Lots of food leads to lots of ducklings, and excessive breeding leads to large numbers of birds in one area. Because ducks defecate directly into the water, they can have a significant effect on water quality & the E.coli levels.

  • Use septic friendly products

Not all products on supermarket shelves are safe for your septic system or the environment. Anti bacterial cleaners, bleach, disinfectants & many other chemicals can kill the micro-organisms in your septic system causing it to fail, and potentially leach runoff into our waterways.

  • Care for your on-site waste water system

Regular maintenance (hi-tech systems need a maintenance contract and frequent servicing) & 3 yearly pump outs will ensure your system is working effectively.  Conserving water by only doing 1 load of washing per day and spacing our showers are proactive steps you can take to avoid overloading your septic system.

  • Pick up after your dog

Dog faeces left on the ground wash into waterways, carrying E.coli and other bacteria that can make people sick.

Take Action - Care for your Septic System

Know Your System

Primary Septic Systems

A primary treatment system is, most often, a septic tank. A septic tank has an anaerobic bacterial environment that settles solids and digests them over time. The digested solids build up to form a sludge and scum layer which eventually needs removing (if the tank is working properly) to maintain enough capacity for settling.

(The treated water is smelly and usually discharged underground – with the discharge trenches needed replacement eventually).

Secondary and Tertiary Systems

A secondary treatment system is, most often, a septic tank, followed by a forced-aeration chamber, or a trickling filter chamber through which air passes. Thus, there is an aerobic treatment stage after the anaerobic stage, utilising a different set of organisms. Thereafter there is settling and/or filtration.

(The treated water can be relatively clear and odourless and is usually discharged into topsoil – which can continue indefinitely, if treatment standards are maintained).

a tertiary treatment system is a good quality, well-maintained, secondary system, with the discharges running through a sufficiently-powerful UV lamp (sized for the flow rate) prior to entering the discharge area.

Know Your Obligations

Primary Septic Systems

Primary (older) systems must be inspected no less than every three years and pumped out if required when scum and sludge levels occupy 50% of the tank volume.

Secondary and Tertiary Systems

Secondary & tertiary systems are required to be maintained by a suitably qualified person every six months. Records of each maintenance action must be retained and made available for inspection by Council or their agents.

$40 septic tank check!

With the support of Project Little Oneroa, Waiheke Local Board and Greenacres Waiheke 100 Waiheke properties can access a 50% discount on a septic tank check. Book now to avoid missing out!

The septic tank can be used to show compliance under the Auckland Unitary Plan for primary systems and can be used as a health check for secondary and tertiary systems. During the check service, providers can unblock drains, assess drainage fields, clean filters, purge lines, sludge measurements, and assess system health and troubleshoot. Post check they will report and provide details of suitable specialists if necessary and also use the time to show people, how to better maintain and manage their systems. Up to 1 hour on site.

For info contact or call 372 2915

Annual Report

Where to get other help

Onsite Waste Water Servicing

Oasis Clearwater
0800 48 48 49

0800 628 356

0800 103 040

Hydrovac service
0800 493 768

0800 466 635

Natural Water and Waste

Mark Bright: 0274890604

Pump Out Servicing

Green Acres
09 372 7614

Waiheke Septic Tank Services
09 372 7015

Waiheke Independent Waste Water Engineer

CBC Wastewater
09 372 9190


Project Little Oneroa is proudly funded by the Waiheke Local Board


Project Little Oneroa is also supported by the Auckland Council Healthy Water team.

Project Little Oneroa supports these United Nations Sustainable Development Goals

WRT's Health and Safety plans are provided by:

The WRT is an Auckland Council accredited service provider: