Does Bindi look like he is straining at all?  How much water is he drinking in realtion to when he was peeing a lot?

This is what I grabbed off the HRS web site: http://www.rabbit.org/health/urolith.html

Straining to urinate. The rabbit takes longer than usual to pass a smaller than usual amount of urine. This straining behavior is frequently mistaken for constipation. True constipation is extremely rare in the rabbit. Occasionally the straining can be so painful that the rabbit will cry out or moan when urinating, although this is rare. You should consider it an emergency if a rabbit is continuously straining without producing urine. This indicates that there may be a complete blockage of the urethra (the tube the urine flows through out of the bladder) and if this is not corrected it could result in the pet’s painful death within 24 hours.

So it looks like a trip to the vet would be warranted or at the very least call them. How long has he been doing this?

yes does sound like it could be a urinary infection but these are usually easily treated when caught early so just get him to a vet and all should be fine

I’m sure of the exact reason for a UTI, but it can be related to bad bacteria that are present and growing, why they take up house in the bladder or how, I am not real certain and will research it a bit more.  But, in the mean time here are some articles:

I know this is an article on urine scald, but it does talk about UTI’s: http://www.bio.miami.edu/hare/urinary.html

Here are a few more:

http://en.allexperts.com/q/Rabbits-703/Infection-urinary-tract.htm

http://www.bio.miami.edu/hare/culture.html