As long as you use a water conditioner that treats both chlorine and chloramines there is nothing wrong with using sink or tap water in your aquarium.
You can use clean tap water for your goldfish, but not dirty or used water.
Yes. I put my goldfish in water strait out of the sink. We have a well so I dont know about city water, but I know that you can put well water strait out of the sink. Hope this helps.
yes very very bad
Since they are not fed live food, their method of catching is swimming after food that may sink in the water
Partical stoppage / Bad venting
As long as it's not flavored, you'll be fine.
mybe it needs to git its water cleend
Actually, yes, if the ant were in the water.
Yes. goldfish breathe water so if a goldfish is out of water it cant breathe so it will suffocate
Bad eggs don't sink they float.
All I do is get water from my kitchen sink for my betta fish, goldfish, and tetras. I do the same for my cleaner fish. They like it a lot. I also sometimes add tap water, but they are fine without it.
The fish will look and act lethargic, also you can tell if the water is bad by doing some simple water quality tests.