I travel around a lot with my job on a daily basis visiting several locations. I have a work partner and we often have to make 7/8 different calls in a day which can often be an hours drive initially and then 25/45 minutes in between visits.
I’m 25 weeks pregnant and I get so dehydrated if I don’t drink 2/3 litres of water a day, however, this means I am constantly needing the toilet so my colleague who is the one who does most of the driving is getting quite annoyed. It can’t be helped but I’m now in a position where I’m too worried to ask him to stop as it often means we have to pull over and look for a toilet on the sat nav 
I’m not sure what I can do, if I speak to my employer there’s not much they can do, as they can’t monitor his behaviour 24/7 and equally I’ve still got 3 on the left of working with this man so I’d rather not rock the boat!!