You could try a trash bag -- I've used those large black 30-gal bags a lot for my padding setups, but I've also used em in the shower & pumped em full of water.
They *generally* don't leak, but you can test its airtight-ness (get a bunch of air in it and squeeze to see if any air escapes) before doing it with water. Double-bagging is another way to protect your house from water damage lol. I'd recommend doing it in a bathtub or shower though just in case.
Have it under a layer of shapewear, and maybe put a belt on over top of the shapewear and lower than the bag to make sure the bag doesn't fall through - it gets *heavy*. You'll also probably want to tie or duct tape the bag opening over the hose so that no water spills out the top
2 weeks
