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Wastewater overflows

Contact Watercare first ​on (09) 442 2222 if you are experiencing an overflow or
wastewater flooding on your property



Our wastewater network is designed to protect public health so in the event of heavy rain, pipe blockages or breakages, wastewater will overflow into the environment - through manholes and engineered overflow points - rather than backing-up in pipes and flowing onto streets or back into your home.

Wastewater overflows occur primarily in wet weather but can also occur in dry weather as a result of blockages:

Wet weather overflows

Our network pipes are built to handle five times the normal wastewater flow to accommodate stormwater that enters our network during rainfall.
Wet weather overflows can occur during heavy periods of rain when the volume of stormwater exceeds the capacity of our wastewater pipes, pump stations and treatment plants.
These overflows are exacerbated by old, leaky pipes that have not been maintained over the years, allowing stormwater to seep into our wastewater network, and houses and buildings that have their stormwater downpipes connected to our wastewater network.
Both factors can greatly increase the volume of heavily-diluted wastewater being transported and treated by our treatment plants.

Want to know more? Here's what you can do to prevent overflows.

Dry weather overflows

This type of overflow is most commonly caused by blockages that can arise from waste inappropriately disposed of down private household drains.

Most wastewater pipes are only 100mm (four inches) in diameter and are not designed to carry anything other than wastewater and bio-degradable products like toilet paper.

Wastewater that enters our network consists predominantly of water; however, it also contains human waste, food scraps, fats, debris and trade wastes. Over time, fats, oils and grease build ups in pipes, eventually causing blockages.

It is important for all of us to be aware of what is being disposed of down our sinks, toilets and pipes. Some things best disposed of in the garbage bin, rather than down your drains and into our network, include:

Tree roots can also cause dry weather overflows. If you are planting trees on your property, it is a good idea to check that the tree is not going to grow over your pipes or ours.
As trees mature so do their roots and, in time, they can reach pipes and damage them, collecting debris, obstructing the water flow and eventually causing a blockage or break.