Wellington Water’s successful location and repair last week of the broken pipe that led to increased bacteria levels at Titahi Bay in late February underlines the importance of dedicated resource for this work.

Investigations into sources of contamination in streams and coastal water are complex and time-sensitive. Minor local sources such as bird and animal droppings can provide contaminated results, while rainfall dilutes stormwater, potentially making following the contamination trail impossible. Causes such as cross connections from wastewater to stormwater pipes or damaged pipes provide intermittent flows, so contamination is not constant. As a consequence, some issues can lie undetected for years, while tracking faults can take weeks and sometimes has to be delayed as more urgent repairs take priority.

Recognising the positive impact that finding and fixing these problems will have on the city’s harbour and coastal water quality in the long term, Porirua City Council is planning to fund a dedicated team to focus on this work.

Late last month high levels of bacteria were found near one of the four stormwater outlets to Titahi Bay beach through council-owned Wellington Water’s regular water quality monitoring programme. It led to a public health advisory against recreational bathing and other activities in the area but the all-clear was given two days later when bacteria levels subsequently decreased.

Wellington Water’s investigation team continued to try to identify and resolve possible sources. Collecting and analysing samples from key points in the stormwater network, the team methodically worked their way upstream from the beach, following the trail of contamination. The broken wastewater pipe connection was identified approximately a kilometre from the beach and fixed the following day, well ahead of the Titahi Bay Festival on Saturday. Wellington Water is continuing to take samples in the area, in case of any other potential sources of contamination.

Wellington Water advises homeowners to engage a plumber to assess unexplained areas of dampness or odour on their property as soon as possible, while tenants should report it to their landlord or property manager.

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