A handful of activists at Vancouver's Oppenheimer Park, home to more than a hundred people living in tents, have occupied the bathrooms in an effort to prevent city officials closing them again, according to advocates.

The park's public washrooms were closed overnight Tuesday, leading to hygiene concerns from some who live in the park.

"There wasn't any information about why that happened," said Fiona York, co-ordinator with the non-profit Carnegie Community Action Project.

"And there was no advanced notice."

She says the only warning was a handwritten note stating the facilities were closed.

According to the City of Vancouver, the closures were due to the discovery of a sewage backup. Plumbers are expected to be on site Thursday morning, and the washrooms will remain closed until then.

Roughly 150 people currently live in the tent city, York said, and access to washroom facilities is crucial.

"Sanitation, running water and toilet access is the number one health and safety concern," she said.

The city says there are four portable washrooms on site.

York emphasized the purpose isn't to shut down repairs but rather push for adequate, alternative sanitation facilities.

"There's no running water so it's not a great solution," she said. "The discussion is about setting up something in place of the washroom."

Oppenheimer Park's tent city has been an ongoing, contentious issue for months.

Last month, the park board voted against evicting people living in tents, choosing instead an approach to help them find alternative housing.

This after the Vancouver Park Board resettled around 100 park residents into single resident occupancy (SRO) housing or shelters over the summer — about two-thirds of the people who had been living in the park at the time, according to the city.