How long is it healthy for a baby to hold his bladder?

[YangLiQiu]

I haven't exactly decided to full time EC yet but apparently my almost 6 month old has.  I was delaying starting full time because my parents came to visit and we were doing a lot of travelling but my baby is literally going for hours on end holding his pee until we take him!  I'm wondering, how long is it healthy for a little body to hold it for?  Because sometimes, its four + hours and I'll take the nappy (diaper) off because he still hasn't peed.  He's not asking to pee and its beginning to worry me a bit because even when we take him, he's telling us he doesn't need to go.  He doesn't seem to be in any pain or anything so I'm sure he doesn't have an infection.  

The other funny thing I've noticed is that he has places he 'prefers' to pee in over others.  For example, we live in China and he absolutely refuses to use toilets that smell very bad or troughs (don't really know how to explain that).  We have a regular toilet in our house and he has let us know that he prefers to pee in that or on a tree...is this normal for a 6 month old?!  I didn't expect him to be so opinionated!!!

[nilatti]

My little guy (7.5 months) has started "holding it" for surprisingly long periods of time when we're out and about. For example, we potty him before we leave for church at about 8:30 am. We don't get back until 12:30, most Sundays. Sometimes there's a meal after the service, and then it could be 2 before we get back. A lot of times, he'll fuss and act like he needs to go, but refuse--and he stays dry. He hasn't had any UTIs or anything like that, so I'm not too worried.

I've started carrying the Pottette in my diaper bag and offering that in hopes that he can relieve some pressure. So far, he's not been too into that.

I will say that lots of ECers report that their babies are dry all night as young as 4 months (and mine was at around 5 months, until he started sleeping more lightly because of teething and a cold and an ear infection...hoping we get back to that!). So that would mean not peeing for 8 hours or more. I've never heard of them having any problems from it.

Of course, I'm not a doctor. I would ask my doctor about this, but I really don't think he'd take me seriously. "A baby? Hold it? They can't HOLD IT until they're 2!"