Would you be preapred to resign over the issue?
When i worked in business alt of jobs such as cleaning coffeee cups, cleaning phones and emptying bins by our desks was done by cleaners, but gradually these roles were elominated/cut back in order to make 'savings' and everyone from post clerks to highly paid managers were expected to empty their own bins, clean PC screens etc. I think you have to accept that. I was never asked to hoover carpets etc but if I had I would have smiled as I did it, thinking that I was being rather well paid for doing such a task. If anyone didn't like it they were free to look for other jobs.
Unless these duties become a fairly large part of the role (15%?), or require specific training and protective clothing, or are allocated in a discriminatory way (women clean toilets, men change the light bulbs), I don't think there is anything unlawful in it