Sanitary waste contracts

Sanitary waste - Does anyone know the legal requirements re sanitary bins? We have lidded bins in each female toilet for sanitary waste which are lined with plastic bags and emptied regularly by our cleaners. We were visited recently by a company which provides and collects sanitary bins, who suggested what we were doing was not legal. When I have googled it, most answers on Google are from sanitary waste product companies, so of course they will say it's not legal. Do I need to take out a sanitary waste contract?

Lynn Manktelow