Access to fresh water....

Hi everybody!

We've just finished installing a fence for our dog and he is going to
be outside during the day while we are at work.

Do they make dog waterers that only put out water when the dog is
licking it? Sort of like the have for hampsters only much bigger?
We want something so that bugs won't get in his water and so that it
will stay fresh.

For now we are just using a bucket, but it usually gets pretty dirty by
the end of the day.

Thanks.