Bearded dragons have no concern for water dishes being fouled etc. To them its just part of their environment and they go as the urge takes them. Normally, in the wild, bearded dragons will have little to no contact with their droppings, and water holes/puddles probably are very big, or dry up after while.
If he keeps soiling his water dish, give him a smaller one.
For a three month old dragon, I will continue feeding him as often as you are now, but increase size of crickets as needed, so they are still within the distance between the dragon's eyes. I also suggest giving him as many crickets as he can eat in a 5-10 minute period per feeding. A dozen crickets a day is rather low.
Once he is about 6 months old, or there abouts, you can cut back to one insect feeding a day with salad available all day.
Around 12-14 months old, you can cut back on insects to just a few insects a day (about 10% of his total diet_) or a couple feedings a week, with a healthy mix of greens and vegetables given daily. Adjust so your dragon doesn't get too fat etc.
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PHLdyPayne