My hot water heater started leaking today, so I turned off water to my house at the curb. After the tank was drained, I disconnected the cold line and turned off the valve right above the hot water heater.
When I turned water back on at the curb, water started coming in to the tank from the hot line, eventually reaching ~0.5gal/min coming out the drain.
There were no faucets on in the house. What can cause this behavior? My hypothesis is that it could be the shower mixing valve but I'd like to confirm it's just that and not something more... sinister. (lots of lousy DIY work in this house from the previous owners).