Background: Recently bought a home. Has a well that seems to be only connected to outdoor faucet. Also has a soft water system but we can't turn it on because a hose to the washer from the soft water unit has no where to connect. We are connected to the city sewage and water system.
Question: If you don't use the downstairs 1/2 bath toilet toilet for a day or two the toilet bowl water will start to turn black and also the bowl. Sometimes will smell a little like sulfur. The tank is clear with no odor. We've also noticed that the upstairs toilets (there are 2) get a dark ring around the bowl within a couple days of cleaning but no odor. What could be causing this?