Septic tank search on
Unregistered septic tanks in Titahi Bay could be the cause of beach water contamination recorded last summer.
Two coastal sites in Titahi Bay were repeatedly too polluted to safely swim in over the summer, according to a report released two weeks ago by Greater Wellington Regional Council.
The sites, near the rowing club by Onepoto Park, and by Access Rd at the south end of Titahi Bay Beach, exceeded national recreational water quality guidelines on six and five occasions respectively.
The problem is likely to be caused by faulty cross-connections between sewage and stormwater pipes, Porirua City Council’s harbour strategy co-ordinator Keith Calder says.
‘‘ It’s sewage getting into stormwater, stormwater getting into sewage.’’
Rainfall often causes pollution in the harbour, as contaminants are washed off urban areas and farmland into the water, but last summer’s pollution did not correspond to rainfall. ‘‘It’s coming from some sort of pipe system.’’ Septic tanks in Gloaming Hill are suspected as a cause of the contamination, which the council is currently investigating.
Before 1940 septic tanks did not have to be registered with the council, so Mr Calder’s first job is to find the tanks, as the council has no record of them.
‘‘It will take a long time to get to the bottom of it, no pun intended,’’ he says.
Once located, any pipe leaks will be repaired using $2 million set aside for pipe repairs this year, part of a $30m council budget over the next 10 years, Mr Calder says.
‘‘There’s now a fixed plan to upgrade the systems.’’
There is no serious heath risk from the pollution, as the affected areas are not popular swimming spots, he says.
A number of waka ama rowing groups launch from the Onepoto site, but are well aware of the contamination issues.
Bacterial and viral pathogens were found in the water last summer, including E. coli, salmonella and campylobacter, and bathers risk illness and infection at peak pollution times, he says.
‘‘Certainly there’s some sickness and some infection from cuts.’’
Beach users should avoid the water after heavy rainfall any time of year.
‘‘The general rule is don’t go covering yourself in harbour water after rainfall.’’
Council senior environmental health officer Nick Macdonald has not heard of any sickness resulting from Titahi Bay’s water pollution.
The council puts warning signs on beaches as soon as pollution is recorded two days in a row, he says.