Photo of discolored water in toilet bowl.

This post was edited by SBWalker on Mon, May 6, 13 at 20:49

My first suspicion would be a clogged/blocked vent line. Running a snake down from the roof, long enough to reach the drain line, may clear the problem.
Are you on a septic tank or sewer? If a septic tank, which level are these toilets on?

On city sewer system.

"toilet water porting problem" Not a term used in the plumbing trade. I suspect that this is not a serious post. But if it is, one test is to quickly pour a bucket a bucket of clean water into the toilet bowl. Watch how it flushes and how the remaining water looks after that.

Sounds like an incomplete flush.

Try holding the handle down longer till the tank is empty (no more water from under the rim when flushing).

A flapper that closes to quickly will not allow the tank to empty far enough.

A new clue. The third toilet in the house, in a guest bathroom, has been used lately, and it, too, now has brownish water in the bowl.
Sounds like snaking the vent line is the first fix to try out.
Thank you all for sharing your ideas as to how to fix this.