Make sure you are filling the bottle all the way to the top and screwing the lid on very tightly so nothing leaks. Is is possible that your guinea pigs are emptying or playing with the water? Some piggies have peculiar habits like that, and a couple of mine like to make a mess- although they don't actually empty the whole thing. Another issue is if the cage moves around as the piggies run, and this can cause the water bottles to leak. I use several layers of mattress pads and fleece to absorb all the commotion and it keeps the cage from rattling, plus it's on a sturdy table.
I have nine 32-ounce water bottles through the cage (it's big and there are 11 piggies in there!) and they were all really cheap from Walmart, and I never have any problems with them. I also use the bricks since there's always a little dripping from my messier drinkers.