I'll ask my mum, becuase I used to do it all the time.
shampoo, conditioner, bubble bath - anything with a lid was a challenge and it all got poured down the bath.
And it wasnt just at home. I did it at other peoples houses as well.
I think I liked watching it all go down the drain, so the only think I could possibly suggest is one of those water, or sand and water play tables? Possiblt not the best thing with winter coming though.