The case against cross-connections

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Many people who live in cities don’t give the water networks beneath their streets a second thought.

In Wellington, with so much coastline and beautiful harbour water to enjoy, we all need to know that we can make a difference to the quality of our marine environment, just by being aware of how water networks work.

For example, did you know the water that goes down street-side drains and from your roof is not treated? It is piped into streams or directly to the sea. Only large items that end up in the drain are screened out or trapped – everything else empties into the harbour or coast.

Wastewater is carried through a different network of pipes that leads to the Moa Point, Western (Karori), Seaview or Porirua wastewater treatment plants.

Cross connections directly affect our environment

A cross connection is the diversion of stormwater into the wastewater network, or wastewater into the stormwater network. A common source of cross connections is a downpipe diverted into the ‘gully trap, the drainage vent usually covered with a small grating and located against the outside of a house, near the kitchen, laundry or bathroom.

Stormwater in the wastewater network increases the volume at the treatment plant by up to five times dry-weather levels. It can overload the plant, leading to a discharge to sea of only partially treated water.

Wastewater connections to stormwater pipes have an equally harmful impact. Due to a faulty connection or leaks, wastewater does end up in the stormwater network. These cross connections are illegal.

It is the homeowner’s responsibility to ensure their drainage pipes connect to the right system. If you are getting drainage work done for an extension or new development, ensure your drainlayer is 100% confident your pipes are going where they should.

That way we’ll keep our streams, coast and harbours clean for generations to come.

For more information, check out our factsheet below.

Related documents

Cross-connections factsheet - Oct 2015

420 KB | pdf | 19/07/16