Delta Classic, Single Clear Knob Handle 4-Inch Centerset Lavatory Facuet wi "replace tap washers shower" Questions

water is coming out the mixer tap and the shower head at the same time when it should be coming out the shower only do you have a 3 handle diverter?If so you must replace the washer on the middle stem

...water bad If its a ceramic cartridge type then replacing cartridge is called for, HOWEVER sometimes cheaper to replace complete tap. If not ceramic then turn mains off and replace the washer