The Equality Act does not say what particular services have to be provided on a separate-sex basis. 

As everyone knows, some locations have only unisex toilets (such as on a train). Others have separate-sex facilities. Some have both. 

There are several laws specifically about providing toilet facilities, in particular in workplaces and schools. And not providing adequate toilets for both men and women would be sex discrimination. 

The specific laws about toilets make clear that a fully-enclosed room for a single user as you have at home or separate male and female washrooms containing stalls or urinals (or both) are both considered adequate. But traditional cubicles in a room that is open to both sexes are not adequate.

What is provided in practice will depend on the size of the building, how busy it is and so on. In some buildings, such as small cafes or offices, and on trains, there may only be space for one toilet which is for everyone. In places like larger offices, pubs, concert venues and football stadiums, it is much cleaner, safer and faster if there are separate facilities. 

Schedule 3 part 7 of the Equality Act allows service providers to offer single-sex and separate-sex services. This includes toilets. At Schedule 3 paragraph 26, it provides several “gateway conditions” that provide the legal basis to allow service providers an exception to sex-discrimination rules – this is what makes it lawful for service providers to provide single-sex services. These include:

“Where the service is provided for, or is likely to be used by, two or more persons at the same time, and the circumstances are such that a person of one sex might reasonably object to the presence of a person of the opposite sex.”

and

“Where the service is also provided jointly for persons of both sexes, and the service would be insufficiently effective were it only to be provided jointly.”

This recognises that some services might be provided separately, jointly (to both sexes) or with a mixture of options. 

There is no similar exception needed for workplace toilets, since it is a statutory requirement to provide adequate male and female toilets at work.