Oh yeah a bowl would work fine since you're with them to watch them all day. Anything deep enough for them to get their entire heads in will be fine - but small enough that they can stand in if they do get into it. I used a one gallon automatic dog waterer for a while - until it wasn't deep enough anymore. Aren't they just the cutest when t hey are swimming!!!???!!!

I also had duck diapers for a while until I moved mine outside. You can buy them online and someone may post the link - i honestly can't remember... A lot of BYCers use them when they keep their ducks indoors.