zochalin is דאורייתא, nine kavin is much better than nothing
a rubber plug is not a kli because it is not meant to hold anything inside, and because its only use is when מחובר לקרקע
@ExGingi even if rubber is mekabel tumah (source?), if there is no בית קיבול its not mekabel tumah (exept metal)
if it actually leaks, even a drop its zochalin, thats why i wrote "if u have a good plug"
@yelped i would imagine that the metal handle doesnt make the rubber plug a kli because its only משמש the rubber and isnt the עיקר, not 100% sure
@Dan i have the new standard israeli bathtub at home and its not 335 liters, dont know whats standard in usa