Fresh water tank

Hi... Can someone tell me if the fresh water tank can be filled to the top. The trailer is going to it's new home Saturday, and we want to be sure the tank is clean. We filled it to the top and added about 1/4 cup bleach. We plan to leave it like that overnight. Neither one of us can remember what we've read about it. So, if anyone thinks it's a bad idea or if it's okay, please let us know.

Also, how do you get the FW tank completely empty? We've never been able to do that.

Thanks,
Jo Ann