Wellington's 'guilty secret': Legacy landfill seeps orange sludge onto popular beaches

A legacy landfill that's seeping orange sludge onto a popular beach on Wellington's south coast is not the only coastal town affected by the problem.

For decades, Houghton Bay, a southern suburb of Wellington, has been plagued by an orange liquid that smells of diesel and comes from the old landfill.

Wellington Water tries to manage the contaminated groundwater, also known leachate, by diverting it into the sewerage system. But this doesn't always work, and the network can become blocked or overloaded.

Locals say the leachate is so offputting even dogs won't touch it.

Rochelle Gilmoni, a Houghton Bay resident, says she is surprised nothing is being done about it.

"It can't be good for the environment, it's not very pleasant for the residents who use the beach a lot."

For years, residents have been calling on the council to find a solution. 

They say it's unacceptable to have pollution leaking onto the popular beach.

But David Filer, a local of 25 years, says fixing the problem would be a mammoth task.

"There must be a huge amount of old rubbish buried under the fields up the hill. Unless they dig up the entire valley, I don't know what they can really do," he told Newshub. 

In Wellington alone, there are hundreds of old landfills. 

Wellington Water's Ben Fountain says this is an example of our wasteful past catching up with us.

"In New Zealand, we've got a guilty secret, and that guilty secret is that we've been a wasteful people - our lack of population density has meant that we've got away with a lot of things," Fountain said. 

The landfill closed in 1971. But even after 50 years, each time there's heavy rain, the water picks up contaminants from the buried waste, runs down the hill, and seeps out onto Houghton Bay beach. 

Wellington Water says it's happening more frequently than ever before.

This is not just a Wellington problem.

Earlier in the year, rubbish was strewn across 300km of a West Coast beach, after a legacy landfill was breached when a raging storm hit Franz Josef.

Other coastal towns have experienced similar issues due to erosion.

"It's taken 100 years to get to where we are. It's going to take a lot longer to fix all of those mistakes," said Fountain.