I used to be the only member of staff in a public library - I had to work through my breaks and I couldn't go to the toilet cos I was then leaving the library unmanned. I did it for 4 years and it wasn't ever a problem, even when I was pregnant. How much do you drink that you need to go to the toilet more than 3 times throughout your working day? If you also go at the start and end of your shift that's 5 times in what - 8 hours? That seems a lot. If you have a health problem maybe you could get a dr's note.