Sorry but My DD who are 5 and 8yo go in with us and are well behaved. Mybe since we have our own hot tub I don't see what the deal is. Yes I agree rowdy children and ADULTS should not be allowed in. If kids are well behave and supervised whats the problem? I have seen "20 somethings" drunk in the hot tubs who I am sure were more likely to pee in it then my daughters.
) in the tub. I think they have every right to be there as long as they're using the hot tub for it's intended purpose. We all could use the relaxation that the hot tub offers, no matter what the age, again, unless their young age or bodies would cause a health risk for them. 
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