It leaks if you close it with the lid that has a straw and turn it. It closes very well and doesn't leak at all with the regular lid. Its construction is very good, the lids are made of thick plastic that doesn't seem to break easily. We have been using it for a while and it has some small dents from falls, but nothing terrible. The only downside is that the straw is very difficult to open, even for adults. I expected it to soften over time but it didn't.