The toilet is new. (Installed abut a year ago) and in good condition. The trap does not dry out. It is on the top floor of my house and the other toilets don't have the same problem. I have no reason to think the vent is plugged since I'd doesn't gurgle and the sink drains fine. The shower drains slow but it always has.
If the toilet is unused for 10 hours it gets an oily sheen on the water and smells bad. If it sits unused for a week the water turns black and it smells terrible. The toilet is mounted about 18 feet above the city sewer line (second floor)
The basement toilet has a pump which pumps the waste up about 4 feet before it flows down into the sewer line.
That is all the relevant information I can think of.
Any ideas?
If the toilet is unused for 10 hours it gets an oily sheen on the water and smells bad. If it sits unused for a week the water turns black and it smells terrible. The toilet is mounted about 18 feet above the city sewer line (second floor)
The basement toilet has a pump which pumps the waste up about 4 feet before it flows down into the sewer line.
That is all the relevant information I can think of.
Any ideas?