The rule changes will mean women visiting the women-only section of Basel's Gartenbad Eglisee can now swim topless, in standard bathers, or in close-fitting burqinis - swimming suits for Muslim women that cover the whole body apart from the hands, feet and face.
However, women won't be able to enter the water in underwear or in the looser style of burqini which has become fashionable in parts of the Muslim world in recent years.
The rule changes also mean only women aged 16 or over can access the women-only pool, known as the Fraueli. An exception will be made for babies and toddlers of both sexes. Entry in street clothing will no longer be allowed.
Local sports authorities have defended the rule changes saying they will combat overcrowding at the pool, which is, according to the rules, a designated “quiet zone”. The ban on looser burqinis, meanwhile, has been introduced because pool staff can no longer distinguish these garments and street clothes, the director of Basel's sports department Peter Howald told Swiss media.
But the rule changes at a facility popular with Muslim women from the Alsace region in neighbouring France come in the context of ongoing problems at the venue.
In summer 2015, the women-only pool was the site of “numerous” confrontations between long-term users of the pool and sometimes “disrepectful” Muslim guests, Howard told the Tageswoche newspaper.
The sports director added that Muslim families were using the pool's lawn as a place to have picnics.
“This is a women's pool and not a women's park. And it's not a pool for children,” Howard said.
The official was also keen to stress the rule changes had nothing to do with religion.
“The most important issue is space. Muslim women shouldn't be pushed away because they are Muslim, but the pool is reaching capacity and we have to deal with it,” he said.
It's an attitude that has not gone down well with local Muslim groups.
Basel's Muslim Commission, which represents 20 local Muslim groups, says it previously tried to work together with local sports authorities, offering to distribute flyers outlining the pool's rules to mosques near the Swiss border in France. But the offer was ignored, according to commission member Serhad Karatekin.
Karatekin also criticized the new rules.
“Maybe it's just about limiting the number of Muslims and the difficult women were the perfect justification to do so,” he said.
At the pool, meanwhile, guests see the problem as having two sides.
“As always when different cultures come together, there is also a lack of respect,” pool regular Brigitte told the Tageswoche.
“But to label all Swiss people or all Muslims as disrespectful is unfair”.