Arrived to customers home for a plumbing service call on a leak in basement customer thought was cause by toilet flange, and another toilet customer thought needed a flapper. When arriving at house we noticed a stain on pop out ceiling in basement caused by water leak that happened in the last few days. Water dried up because customer stopped using one of the upstairs showers in the house, which the leak could be caused by. Most probable cause is the leak is cause by a drain pipe in shower or connecting sink and shower upstairs going into basement; or shower body in upstairs shower, because leak only happens when customer runs water in shower (More cold side then hot side). Customer stated she doesn’t feel the need to fix the shower because they do not use that one anymore and have 3 other usable showers. Customer will call us in future when she gets bathroom worked on and re-done to fix problem. Constant running toilet seemed to be air coming from fill valve and there were no visible