Waikato homeowner fears flood basin will devalue her property and could inundate her home

A Waikato woman fears her home has been "drastically devalued" and could be inundated with water after developers built a large "pond" on a hill just metres from her property.

The pond - which sits at the same height as her roof - is part of the flood management system for a 70-home housing development in Tuakau, 70km south of Auckland.

But primary school teacher Katrina Fricker claims Waikato District Council didn't notify her it would be built just 8m from her house.

Given the pond's elevation, Fricker fears that should it fail or overflow in a major flood then thousands of litres could spill into her home.

Developers GDP Developments say the structure has full council approval.

The council says that rather than causing flooding, the structure is designed to prevent it.

Known as a dry basin, it won't permanently hold water, but instead collect it during heavy downfalls and drain it in a controlled way, council said.

The risk to nearby properties had been fully evaluated, it said.

However, Fricker said she'd been warned by a real estate agent it could be hard to sell her house and that it had become a curiosity among locals, who've labelled it the "home under a pond".

"I'm struggling at work because this is on my mind, I'm waking up at 4.30am and already thinking about the pond," she said.

She sees her concerns as an early sign of what could become a growing tension between new housing developments and neighbours during Auckland's building boom and the onset of climate change.

Katrina Fricker's home and the flood management basin. Photo / Supplied

She understands the need for new housing, but said it's important it doesn't devalue nearby properties.

She spent 25 years saving the deposit for her home and now has much of her life savings wrapped up in it.

She also claims earthworks from the construction of the flood management basin shook her house, causing cracks to open in the walls.

However, because she doesn't have photos or other proof of the home's condition prior to the earthworks, it is hard to lodge an insurance claim.

She claims developers have promised to send decorators and painters to her house if insurance can't cover the alleged damage, but she doubts this will restore it to its previous condition.

Katrina Fricker of Tuakau worries a new 70 home development above her property has drastically devalued her house. Photo / Alex Burton

She also said water draining from the flood management basin was initially directed through an easement on her property.

And while the pipes have been redirected, an emergency spillway for the basin - which is activated when the basin fills up and is overflowing - will still be directed through her property, she said.

Fricker's main problem however is the pond itself.

Prior to the land above her property being bought by GDP Developments, it was used as a market garden.

Katrina Fricker says she's not getting any sleep for fear the home she spent 25 years saving up to buy has lost much of its value. Photo / Alex Burton

Fricker said water had flowed into her property until 2017 when the garden owners built drainage trenches - after which it never flooded again.

She said that was a much better system than now pooling all the water directly above her house before draining it away.

A spokesman for GDP Developments said council had approved all building consents for the development.

"The developers have worked pretty hard to try and address any concerns, they have met with Ms Fricker a number of times," he said.

"If she still has issues she needs to talk to council because it's all been signed off and everything has been done per the consents."

Sue O'Gorman, Waikato District Council general manager customer support, said the land has been zoned residential since the mid-1980s.

"Council encourages people to be aware of the zone they live in, and to know what the land in their area can be used for," she said.

She said council staff had been in regular contact with Fricker and visited her property.

Katrina Fricker says the basin is just metres from her back fence and home. Photo / Alex Burton

Having "carefully considered" Fricker's concerns, all testing and geotechnical assessments had shown "a level of safety factor that exceeds all requirements", Gorman said.

"The dry basin has been designed to cope with a greater than 250-year event".

"The design process is very robust and has been reviewed by Waikato Regional Council and their specialist stormwater engineer."

She said the basin is designed to stop water runoff both during the current construction of the new housing development and after it is completed - at which point council will take ownership of the basin.

Gorman said it was sometimes necessary to position drainage basins at elevated positions above other properties, with several other examples in the Waikato District.

However, Fricker doubted the accuracy of flood modelling and feared natural disasters, such as floods, could become more common with climate change.

Jonathan Wood, senior property lawyer with Court One, said the use of retaining walls and other flood management tools in areas elevated above other properties was common in the Auckland region's hilly environment.

The failure of these devices is uncommon and didn't feature in many lawsuits, he said.

Still, when building works are undertaken, especially large ones like this, it is important under law that they do not adversely affect neighbouring properties.

He urged Fricker to hire a lawyer to review the housing development's resource consents if she has concerns.

Fricker said a court battle against a developer and the council on her teacher's salary was out of reach.

"I've driven around to several other developments in the area and there is not one where there is a house under a pond," she said.

"It's causing me so much stress."