It took me forever to find a water bottle holder that would function for my cage. The grids around the loft are only 6 squares high which didn't permit most bottles to be positioned high enough. The holder pictured below is the one that works best for me. My husband did a small adaptation in that he drilled a hole through both of the upright pieces and put a short bolt through the hole. By tightening the back piece to the main part, it was secured in just the right place.
I bought mine at PetSmart. Almost any generic 16 oz. round bottle will fit it.
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