Diverters in your water lines keep water flowing to the faucets you turn on instead of allowing it to flow to other faucets. Over time, diverters can wear down or fail to close completely, usually because of calcium deposits or a buildup of other minerals.
Diverter failures allow water to flow other faucets, so if you turn on your shower and a diverter doesn’t funnel all the water in that direction, water may come out of one or more faucets. A plumber can repair or replace the diverter and remove any buildup as needed.