Wellington Scoop

The real risk from sewage in Titahi Bay

by Michelle Laurenson
Yesterday’s claim that there is “very small risk” to the public from the latest sewage overflow into Titahi Bay is misleading, and such propaganda used by Wellington Water is extremely concerning.

Titahi Bay’s Treatment Plant has a discharge pipe just 500m from the beach and the plant overflows in heavy rain. When three to five times higher flows reach the plant, its hydraulic capacity is unable to treat the high volumes. Documents provided by expert engineers for the re-consent application are very clear on this. In heavy rain, large volumes are not treated by the plant.

The risk to the public is known after a discharge – which is why yesterday’s ‘advice’ from Wellington Water suggests no swimming until 48 hours after heavy rain.

But the discharge monitoring and sampling at Titahi Bay beach does not occur until 24 hours after the discharge has ended. This can be several days after sewage has poured into the sea and when contamination levels (after two tidal flows) have recorded high faecal counts. The risk to the public is high at the time of a discharge. But notification is often long after the discharge is over.

The frequency of discharges has been increasing with larger flows due to increasing population and frequent heavy rain events.

Upgrades to the hydraulic capacity to cope with increasing flow have been continuously deferred, despite recommendations by the consent authority (the Regional Council) since 2013.

The need to discharge started in 2015 after a collaborative agreement was reached between the consent authority and the consent holder (Porirua City Council) allowing unlimited discharges from the plant until 2023.

Eight years of sewage dumping close to popular Titahi Bay is disgusting. It is dangerous to aquatic and public health and it does not protect the environment.

Notifications that dilute these dangers are irresponsible and do not adhere to the Porirua Treatment Plant Risk Communication Strategy.

Michelle Laurenson is a member of the Titahi Bay Residents Association and Your Bay Your Say.


  1. Stella, 7. December 2021, 22:50

    How does Wellington Water get away with such a carefree approach to sewage overflows?

  2. Henry Filth, 8. December 2021, 5:37

    Porirua City Council really does need to get its sh*t together.

  3. Chris Tingle, 8. December 2021, 12:31

    The discharges have been occurring since long before I retired 10 years ago; the plant can only take 1000 litres per second and even on dry days now, that figure can be reached with the population increase. The plant is only designed for a population of 82,000, imagine what the population is from Pukerua Bay to Churton Park,and from Judgeford in the east which is the catchment area of the treatment plant.

  4. Jeannie Fletcher, 10. December 2021, 20:06

    You would think that addressing such a serious public health issue would be a priority, especially since the public health is a primary concern right now.

  5. P Munroe, 11. December 2021, 13:37

    Porirua City Council did not do anything about a flow into the inner harbor on 7th December south of the Whitford Brown intersection – it lasted about 2hrs plus was clearly seen from Onepoto.