Shower head leaks when other shower is in use.

[teqp]

The shower head in the master bath (2nd floor) will drip some water when the second bathroom shower is on. Also, I had turned off the main water line since we went away for the long weekend. I came back home and saw that water had dripped over the weekend from the master bath. From searching online, there are some that state the shower valve in the master needs to be replaced/repaired. I wanted to see if that is the only problem or if it is something else that is causing this. Any help is appreciated.


Thanks.