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 :
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there's a blockage in the pipes somewhere.
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there's more water than pipes can carry such as in heavy rain.
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pipes are leaking.
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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:
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A connection of stormwater to wastewater
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Leaking of wastewater into stormwater or directly into waterways
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A connection of wastewater to stormwater
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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.