I had a towel on my seat in the car and towels under the sheets on the bed. My waters did break in bed but I felt it happening (it woke me from a light sleep) and I rushed to the ensuite so the big gush happened on the tiles There was a lot of fluid though and I went through a few maternity pads in the 1.5 hours before we arrived at the hossi and my tackies were still soaking on arrival.

It's good to be prepared as it really can throw you and I'm still surprised by just how much fluid the was AND how long it leaked for! Having maternity pads and a change of clothes and underware is great advice along with towels.