Toilet bowl not emptying in upstairs bathroom
My toilet in my upstairs bathroom is not emptying completely. If flushes, but not all the water exists. It's sporadic; sometimes it flushes okay, sometimes not. Maybe once out of every 5 flushes it flushes completely where all the water evacuates the bowl. I have a basement toilet and first floor tolilet as well as another upstairs toilet and they all flush fine. Doesn't seem like it's a septic tank problem but I'm not sure. And it's not a plunging issue as the solid waste (TP, etc.) flush from the bowl even when the flush doesn't appear complete. Any ideas?