We live in a 1920s house with bathrooms on each of the three levels. The basement bathroom is never used, but drains fine when we test it. However, we have had two instances over the past six to eight months where water has literally surged and splattered in the basement shower stall. This was NOT due to use of the basement bathroom, but a temporary backup / spill caused by using the bathroom / kitchen in the floors above. The first instance the backup was limited to a splattering of water from the basement shower stall, which we found because of the staining of the water splash. In the second instance, it was a bit worse in that some water spilled out of the basement bathroom. However, in both instances we did not witness the surge or backup - only found out after the fact based on the small spill of water or the stain. Further, the situation seems to returns to normal immediately and we can now use any of the toilets just fine. In other words, we cannot reproduce the problem, and therefore, are not sure what to fix. Any help or suggestions on how to troubleshoot and solve this intermittent issue would be much appreciated. Thanks much!

I Had a new tub/shower kit with single handle faucet installed in 2011. When I go to use the shower sometimes when I pull up the diverter lever the water only come out the tub spout. I sometimes have to put my fingers in the spout and push up over and over before water sprays out the shower head. Other times I pull up in the diverter and the shower works fine. Why does this happen and how can I fix it?