Investigated moisture near front of house, wet carpet. Investigated wall to find nearby hose bibb in the wall central to the moisture. Cut wall to find grey poly line to hose bibb leaking. Replaced hose Bibb and leaking section of pipe. Majority of house has been repipe in cpvc except for this bibb whose line went below slab. Found thermal expansion tank had failed, replaced thermal exp tank and mounted it to the wall.