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Knowledge Hub / The Network / Wastewater / Knowing Your Pipes

Knowing Your Pipes

The "Knowing Your Pipes" project started in 2021 as part of our work to improve the resilience of our network and reduce the risk of pollution entering our waterways. 

If you've got any concerns or need to talk to us about your property inspection, call us on 04 912 4400. When calling, make sure you quote your reference number, your property address, and details of your request.

Untreated wastewater can go into the environment, if :

  • there's a blockage in the pipes somewhere.

  • there's more water than pipes can carry such as in heavy rain. 

  • pipes are leaking. 

  • there are cross-connections where a wastewater pipe is connected to a stormwater pipe (or vice-versa). 

Identifying the problem

It's an ongoing mission to reduce the amount of untreated wastewater entering the environment. 

Pollution of our waterways can be caused by many different things and there isn't one simple fix. But we're working on making it better. 

There are several ways we identify sources of pollution. 

MONITORING AND TESTING

As part of our Global Stormwater consent conditions, we regularly monitor the water quality in our stormwater network. If a sample from one of these tests is above the trigger levels, we will investigate. During an investigation we will take water samples from different locations to help target where the pollution is coming from.

SMOKE TESTING

We use smoke testing to investigate faults in the wastewater and stormwater networks. To do this, we put a dense and non-toxic smoke fluid into a smoke machine that emits vapour through the pipe network. This testing is looking for four things:

  • A connection of stormwater to wastewater

  • Leaking of wastewater into stormwater or directly into waterways

  • A connection of wastewater to stormwater

  • Pipe faults such as cracks in both private and public pipes.

If we find one of these faults, we’ll work to correct it as this can have a harmful effect on the environment, as well as increase treatment costs.

VISUAL INSPECTIONS

During the smoke test we will also conduct above ground inspections to ensure there are no entry points that allow stormwater into the wastewater network, i.e. Broken gully trap surrounds, low gully traps and a connection of stormwater downpipes and yard drains.

A gully trap is a plumbing feature that should only receive wastewater from your kitchen, bathroom, and laundry. It connects to the wastewater network and is treated. The top of the gully trap needs to be above ground level and partially covered to stop water and objects getting into the wastewater network.

CCTV

We use CCTV (closed-circuit television) to assess pipe conditions so we can make sure the public and private pipes are working the way they are meant to. 

DYE TRACING

If we find a fault and need to investigate it further, we will use dye tracing. This involves pouring a non-toxic, fluorescent green dye into gully traps and drains and flushing it with water. We will then look for places where the dye is released, including private drains. 

FLOW AND OVERFLOW MONITORING

We have installed flow and level sensors in some parts of the wastewater network to help us understand how the network is operating. These sensors aid us to monitor flow levels during rainfall which also helps us predict and prevent wastewater overflows.

HYDROSTATIC TESTING

As pipes age and the ground moves, pipes can become less watertight. This means wastewater might be slowly leaking (exfiltrating) out of a pipe and into the groundwater. This sort of leakage is hard to detect using the other forms of investigation (dye testing and CCTV). In this instance, we may need to do a hydrostatic (or pressure) test to check for water tightness. We can do these tests on both the public and private network.

Assessment 

Faults found in the public pipes will be fixed as part of the council’s programme of renewals.

If faults are found in private drains, we will notify and ask residents to have them fixed. Follow-up inspections will also be carried out.

 

How you can help

As a property owner, you play an important role in helping to reduce pollution in our environment by ensuring that any faults found in the private drains within your responsibilities are taken care of.

To help, please go outside your property and check your downpipes. The pipe from the roof should connect to the stormwater system not the wastewater system. If the downpipes from your roof connect into the gully trap, then you will need to redirect it into the stormwater system.

Find out more about ways you can look after the wastewater network and cross-connections.

Frequently Asked Questions

What part of the wastewater pipes am I responsible for?

It depends on where you live! 

Please check your local council bylaws as there are slight differences. 

What is an easement?

It is quite common for properties to be subject to easements. These are registered over a title for a property. An easement grants one person the right to use another person’s land in a particular way. Two common examples are a right of way (like a driveway) and a water and drainage easement.

A water and drainage easement allows an occupier to pipe water through an area of their neighbour’s property. Easements can be in favour of a neighbouring property, i.e. granting a neighbour access to their property through a right of way, or in favour of a utility company - like Wellington Water.

If a pipe is on an easement, supplying services to another property, is the person who owns the land responsible, or the person who’s getting the service through that land?

If the easement is on your property, but doesn't supply your home, then you are not responsible for it. As for whether your neighbour is, it depends on which council catchment you are in.

If a property is subject to an easement, the owner must allow their neighbour, or a utility company, to enter their property from time to time for the purpose of repair and maintenance and upon completion, restore the surface of the land as close as possible to its original condition.

My property is in one of the focus areas, will my property be inspected?

You will be contacted that an inspection will be conducted as it is based on the sampling of the network and waterways.

Will the information collected during the inspection go on my property file?

Yes. If you or a potential new buyer requests a copy of the properties LIM, the letter issued to the property owner along with the supporting information will be supplied. If you supply evidence of a repair, this will be added to the property file.

I have received a letter asking me to repair stormwater and/or wastewater faults on my properties. Why have I been given 90 days?

We understand how busy tradespeople are now. Please contact your preferred plumber or drainlayer as soon as possible to arrange for them to review the CCTV footage and log sheet. They will work with you to understand what the faults are, repair options, costs, and timing for them to complete the works. Please let us know when you have done this. If we don’t hear from you, we will send reminder letters.

I have received a letter letting me know that my wastewater lateral has some minor faults, is there a time limitation for remediation?

No, however your pipes may become a potential problem for you in the future. It is your decision if you wish to proceed with repair. If you do repair, please supply evidence of the repair so your property file can be updated.

In the video log sheet what do the terms S, M, L and From and To mean?

Small, Medium, Large refer to the severity of the fault observed and logged as per the 4th edition of the Pipe inspection Manual.