A water control system including a showerhead and a tub faucet. The faucet has a valve configured to automatically restrict fluid flow through the faucet and direct fluid to the showerhead as a function of a parameter, such as a predetermined water temperature. The faucet has many modes of operation, including a Reset Mode, an Auto-Divert Mode, a Bypass Mode, and a Cold Mode. A flow control device generates minimal back-pressure when in the Reset Mode such that water does not undesirably back flow to a shower head.