I used the inflatable option in bed for many years and it worked okay without drenching the bed.
You can also buy inflatable baths for bed! You roll onto it and it inflates around you ready to be filled
I couldnt afford one of these at the time so it was just the hair washing inflatable basin i used. (It did the job!)
I might try the rub in shampoo mentioned above, i can't remember the one i tried before but it made me look like i had full on grey hair
@Gingergrrl you're so brave cutting your hair. I have elbow length hair and i desperately needed to cut my hair back in the days when it could only be washed twice a year but i've always had long hair and i decided this illness has robbed me of absolutely everything, its not taking my hair too
I really admire people who go for the cut, i didn't have the balls to do it
I now have an electric bath chair provided by an OT that lowers me down into the bath with a long back rest so i can rest my head back on this while shampooing with my hair hanging over the back of it. If i nod off or pass out mid wash, at least i can't slide down beneath the water anymore. Usually the water slowly sliding up my nostrils was the only thing that woke me and was a bit scary.
Thanks to the bath chair. I can usually manage this once a week now in the bath but where i live now my bath is only 2 meters from my bed so i can actually get to the bathroom these days.
But definitely look into inflatable options, that was the best thing i found when bedridden.