Brass foot valves prevent water from back flowing into the water source. Boshart Industries Foot Valve, Lead-Free, Series: 17YBFVNL, 3/4 in Nominal, FNPT End Style, 200 psi Pressure, 180 deg F, 3.34 in Inlet to Outlet Length, Brass Body, Stainless Steel Trim, NBR Softgoods, 1.4 in L x 1.35 in W x 3.45 in H Dimensions