With no people being involved in any way.... a very sudden change in air-pressure - such as during a storm - might get rid of it.
Iron in the water would cause rusty stains in the toilet.
Water
look in the water tank and see if the water in there is brown too...it might be rust in the pipes
That would be your flush valve in the tank
the reason why the toilet makes noise when you turn water on is because all the water lines are conected so when you turn on water the toilet gets affected and the water that goes down a drain goes to the water pipe.
You would need to use a container of water like a 5 gallon bucket and pour it into the toilet. As you pour it in, the excess water will cause the toilet to drain.
My toilet is doing the same thing this morning. We had a big rain last night. Could this be part of the cause?
Fluctuations in city water pressure. Sometimes this is a bad toilet ballcock. Test by turning water off to one toilet at a time to see if it stops.
A sodium lamp would not disappear when added to water. However the lamp would probably never be usable again.
Hi, I am having a similar issue in my house. I have sulfur smells in one toilet and one sink's water supply. I am also on city water, but I do live in a 100 year old house.
it doesnt matter because the water has evaporated
It can happen several ways; Left alone the water will evaporate, The weather outside maybe windy causing a vacuum across the roof vent pipe, using a sink or toilet on a lower level of your home may cause some reduction of the water level... etc.