Sydney Water employee Reem Yelda was happy to be the poster girl for workplace safety.

When she and a male colleague were asked in September 2015 if they would be photographed for a campaign to promote spine safety, they agreed without hesitation.

It was only once the poster was slathered around depots that the customer liaison officer learnt how her image had been used, and she was so devastated she has not returned to work since.

The poster features Ms Yelda pumping her fist into the air, beneath the slogan "Feel great – lubricate!".

"I just broke down," she said. "There's 70 to 80 men in each depot. Who knows what they were thinking?"

Ms Yelda has lodged a complaint against Sydney Water and Vitality Works Australia, which designed the poster, with the NSW Anti-discrimination Board, which is investigating the possibility of a conciliation.

She is claiming sexual discrimination on the basis that a reasonable person could have anticipated she would have been offended, intimidated or humiliated.

Slater and Gordon principal Aron Neilson said she was seeking financial compensation, but the amount was the subject of negotiation.

"I think it's very serious when you see the effect that it's had on her," Mr Neilson said. "On any common sense view the poster is offensive."

Initially when a bemused colleague forwarded a photograph of the poster to Ms Yelda, she thought he had photoshopped it for a joke, but then a second colleague expressed his concern and it dawned on her that she had been made into a laughing stock.

It was a humiliation she felt more keenly as one of only two women in a team of about 70 people.

"You can't be in that industry as a female without being resilient, but this just broke me," she said. "I worked very hard to get where I was, to get the respect. I just couldn't believe it."

Sydney Water has apologised to Ms Yelda, but it denies the poster contained intentional sexual innuendo.

Vitality Works Australia also sent a message of apology to Ms Yelda following her complaint, accepting that "the content of the image may not have reflected as intended within the poster".

A Sydney Water spokesman said the company would respect the Anti-Discrimination Board's request to keep the matter confidential.

"While Sydney Water cannot disclose the specifics of this matter, Sydney Water's position is that the poster was not conduct of a sexual nature, but a work, health and safety campaign," she said.

The male colleague who was also approached did not feature in the campaign.

Ms Yelda is claiming Sydney Water treated her less favourably than a "non-female" employee in circumstances that were not materially different and, accordingly, she was discriminated against by virtue of her sex.