Mould was present throughout the year, prompting students to seek legal advice.

Tenants of a "horrible" Dunedin student flat have won a confidential payout after an inspection report found toxic black mould posed a serious risk to their health.

The nine female tenants inspected the flat in the middle of 2016, and were told by those tenants it was a typical student flat.

The group signed a year-long lease for 2017, each paying $140 a week.

SUPPLIED A spoon is used as a lock for a door in a Dunedin student flat. The nine female tenants have since received a payout for the state of the property.

But the students, who are studying medicine, dentistry, law and sciences, quickly realised they were living in a house of horrors.

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"I was the sickest I have ever been in that flat," said one of the flatmates, speaking on the condition of anonymity.

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One of the tenants became so sick she developed asthma and a doctor – her flatmate's father – believed mould was the problem.

It was there when some of the women moved into the flat in the new year. It was outside the house. It was on the walls. It was in the fridge.

The property manager later sent a cleaner around, but the tenants remained concerned about the state of the three-level home.

HAMISH MCNEILLY/STUFF The Queens Dr, Dunedin house rented by nine female students that was found to be leaky and mouldy.

As the seasons changed, the problems worsened.

One of the tenants told Stuff that mould began to spread through her room, with the dampness compounded by a shower leaking into a lounge below.

"It is a lot of money for a disgusting flat," one of the flatmate's said.

SUPPLIED Mould contaminated clothing, which had to be thrown out.

The property manager got a builder to look at the problems "but nothing actually got fixed", so the tenants decided to enlist their own building inspector.

His report filed in November concluded the leak affecting the bedrooms could have been present for up to two years, and the home was not water tight. The inspector noted there was a "significant/serious risk" toxic black mould stachybotrys could be present in the wall.

A flatmate said the inaction from the property manager and owner, coupled with their concerns that the issues may never be addressed, prompted them to go to the Tenancy Tribunal.

SUPPLIED Photos of a Dunedin student flat at the beginning of a 2017 tenancy.

Both parties went through mediation, with the flatmates' lawyer filing a submission seeking more than $100,000 against Paul Reuben, of Student Accommodation Ltd, and Blackdog Properties.

"They have endured a poorly maintained and managed residence that has adversely impacted upon their health, safety, and quiet enjoyment of that property," the submission said.

The Christchurch owner of Blackdog Properties, Tim Coslett, declined to comment. Reuben said in an emailed statement "any dealings with our clients is confidential".

The report concerning mould, completed in March, showed the tenants "suffered from prolonged exposure to high concentrations of toxic mould".

"The mould is sufficiently toxic to require those entering the property to wear personal protective equipment, such as specialist gloves, footwear, eye protection, full body skin protective suits, and respirators, and for any soft furnishings and other contaminated items to be disposed of as contaminated waste to prevent others from being exposed to the toxins," the tenants' lawyer noted.

Despite the limited number of tests, there were "alarmingly high spore counts".

Both parties agreed to settle for an undisclosed sum.

A flatmate said they wanted their experience to serve as a reminder for students they should not accept poor housing.