A Palmerston North café is copping a tidal wave of online abuse after telling mums his cafe toilet was "not a nappy changing station".

Barley café owner Matt McNelis says it is hard to put a dollar value on the amount of damage a flood of negative reviews has had on his small business — all, he says, because of a misunderstanding.

McNelis says he was shocked to receive dozens of negative reviews online from people who'd never visited the premises, slamming him for his "nappy ban" in the café toilets.

A mum, who McNelis says has since "apologised profusely", visited the café earlier this week and was shocked to see a sign on the toilet door that read: "This is not a nappy changing station. If you require those facilities, the Plaza will be able to accommodate you much better. Just remember the people who have to clean that mess are the same people who serve you food."

The vegan café is aiming to be one of the first hospitality establishments in New Zealand to go waste free.

The sign is one of the many efforts in that direction, the owner says.

He says the sign is not meant to discourage parents from visiting or make them feel unwelcome. However, disposable nappies are hard to get rid of in a sustainable way and staff have had a number of situations where they found nappies clogging the toilet or even left in the sink or on the floor.

The café only has three staff at any given time and, when the toilet needs unclogging, kitchen service has to come to a halt.

McNelis says that, had the mum asked the staff about it and explained that she needed to change her child's nappy, they would have taken the nappy to the skip bin around the back where they keep non-recyclables.

The mum posted in a local parenting group and, in the space of a couple of hours, the business was flooded with negative reviews from outraged parents.

The woman who runs the parenting group met up with the café owner.

"The lady who originally posted online didn't speak to the staff or anything, just took a photo and posted it," he said.

McNelis says he sat for "a cuppa" with the admin of the local Facebook group and explained what happened.

"I can see how she got the wrong end of the stick, but if she'd spoken to the staff we could have explained," he said.

"It all blew up, people love to be offended."

There were so many negative reviews coming in that Facebook started moderating them and TripAdvisor suspended reviews for the business, to stop the influx.