If water is stored in an old anti-freeze container can it be dumped down a sink or disposed through normal means or is it considered hazardous material?

It depends. It depends on the amount of antifreeze mixed in with the water in the container. It depends on the local ordinances for dumping in the municipal sewer. It depends on who is doing the dumping, private versus industrial. It depends on the size of the container, gallon versus fifty gallon.

Your safest bet is to take it to an oil change location and ask if you can dispose of it there.