If you use a crate or a pen, your dog must have access to water at all times (including overnight) and preferably using a bowl that they can't overturn! This clips onto the bars, is a great size to make sure water doesn't run out and is both more stable than a metal bowl and more comfortable if your pet bumps into it.
It conveniently folds up and out of the way when not in use (which makes it quite handy for taking out on walks too!).
Made of durable plastic and silicone, it's also dishwasher safe.