Please help Found a tortoise/turtle/terrapin

Hi
My partner found a tortoise/turtle/terrapin after nearly running it over. I have put it in a tank with a bowl of water and some veg and salad after being told it was a tortoise but from searching on the internet im totally unsure what it is.. I havent seen it eat any food but it has stayed in the water bowl a long time and obviously if its a turtle or terrapin it needs more water and dif food .. I have taken a picture and would really appreciate if someone has any ideas on what it is..Many Thanks in advance..