I did a similar hike last year.
there will be plenty of water along la verkin creek and at beatty spring. the water at beatty spring is some of the best in the park. so day one will be easy.
Day two, i would fill up at beatty spring before hiking out of the la verkin creek area into the hop valley. there is some water, but its been fouled by livestock and isn't the best looking. My advice is if you are getting a shuttle from springdale to kolob canyons, most will stop off on the kolob terrace road. make sure you driver knows you want to go up the kolob terrace road, and bring a gallon or two of bottled water from the grocery store and stash it at the kolob terrace trailhead. the better camping is lower on wildcat canyon, and the only water source is in the upper portion..
day three. you're first water source will be the spring near lava point in the upper wildcat canyon. its a small spring, and there were a lot of bee's that surrounded the spring. i didn't get stung, but i was very careful not to make any of the bees angry. the water is very good though. As you hike down the west rim, there is a spring off the trail near the campsite at sawmill. i didn't hike into this spring on my trip, but i've heard its good. theres also suppose to be a spring near potato hollow, but again i didn't try to find it on my trip.
day four. there is a well spring (a small pool spring) near campsites #1 & #2 near the edge of the west rim before heading down the steep trail that will take you to angels landing. its a good water source, and your last water source until you get to the grotto trailhead. hike angels landing (its a little crowded on weekends, but its very pretty).
PM me if you have any questions about the route.