Help - small bugs in water bowl?!

[RolyRocks]

Help - I just went to put some fresh water in my hamsters bowl and found a little cluster of tiny white bugs on the inside edge of the bowl. It looked like a circle of white dots and when I looked closer they were moving!! What are they and why were they in his water bowl??
He has a bowl instead of a bottle because I got him when he was older and that's what he had been used to and even though I tried a bottle he never really used it. His water bowl is close to his food bowl and I had a good look in there and couldn't see anything. Obviously I took them both out and gave them a thorough clean but could they be everywhere in his cage?!
I give him mineral water out a bottle daily and have never seen these bugs before... it's making me itch just thinking about them!!
Please help!

Update - Found a couple more very tiny brown bugs on top of his wooden shelf where I keep his food and water bowls. Does this mean a complete cage clean out is required?! I have no idea where they have come from as I freeze food, toys, treats etc!