Water coming out of muffler

Could be normal, could be a problem. Can you provide some more details? Does the exhaust smell like anti-freeze? When the weather gets cold, there will be condensation accumulating in the exhaust system. If you you do many short trips, there will be plenty of water in the exhaust. Do you have to add coolant? If you do not have to add coolant, then it looks like the water in the exhaust is just condensation. Try to take the vehicle on a long ride once in a while to get the exhaust system hot and dry it out.

I agree with the above. Also on most mufflers there is a small pin hole in the back side of muffler. If that little hole gets stopped up you will spray water out your exhaust almost like a pressure washer. Lol. My company truck did this once but after clearing the dirt out of the little hole it went back to normal.

I do have to add water coolant

you got a cracked head or blown head gasket in my opinion. if you didnt have to add water, id agree that there may not be a issue and look into condensation, but having to add water, especially if its a significant amount, tells me you should drain your oilpan. if it has water in your oil as well, you got a serious problem