Lower Hutt residents and businesses are fed up with the stench from a wastewater treatment plant that is so bad it’s making people gag and causing headaches.

The odour has been a long-term problem, but became worse in recent weeks because the plant’s bio-filter is being replaced.

Lower Hutt youngster Millie Boyce had a colourful description for the smell.

“Like you know when your father’s done a massive poo and you go into the toilet after him.”

The smell tends to waft in on a southerly breeze. Some children said it’s unbearable for them to play outside.

“And it’s annoying cos it’s over Christmas time and you want to go outside,” said Boyce.

Kylie Hood said the smell is vomit inducing and making people feel sick.

“Lots of people in our ‘stop the stench group’ have commented about how they get really bad headaches from it but you know the council assures us it’s not bad for our health.”

The culprit is the Seaview Wastewater Treatment Plant, which is owned by the Lower and Upper city councils, and managed by Wellington Water.

Maintenance work is being done to replace the bio-filter, which uses tree bark to minimise odours. The work is on hold over the holidays.

“I think they should have done it before it got this bad,” said Hood.

Since October 31, there have more than 100 official complaints to Great Wellington Regional Council, which has issued tens of thousands of dollars in fines for the terrible smells.

The smell even gets inside buildings. Businesses deodorise, but they’re struggling.

“So most of them are at a loss with that smell because you know it’s really disgusting,” said Yvonne Purua, a supervisor at Junglerama.

A music festival, called Juicy Fest, to be hosted at Hutt Park in the new year could be affected by the smell.

The park is just 300 metres from the smelly plants.

But organisers are confident the event won’t be hindered.

“According to MetService’s extended forecast for the area, any wind expected on the date of the Wellington event are northerlies. This would mean that any unpleasant smells that may still be lingering at that time would be blowing in the opposite direction of the festival site,” said promoter Glenn Meikle.

At a council meeting in November, Lower Hutt’s mayor asked if there was anything more that could be done to control the smell.

“Stop pooing,” was the answer council advisor Bruce Hodgins gave, prompting laughs.

Wellington Water acknowledged the odour has been unpleasant, inconvenient and distressful.

The Hutt City Council plans to spend $13 million upgrading the plant, with the work to be done three years sooner than previoudly scheduled.

Replacing the bio-filter is expected to be complete by January 25.