Brass foot valves prevent water from back flowing into the water source. Boshart Industries Foot Valve, Lead-Free, Series: 17YBFVNL, 1-1/2 in Nominal, FNPT End Style, 200 psi Pressure, 180 deg F, 5.86 in Inlet to Outlet Length, Brass Body, Stainless Steel Trim, NBR Softgoods, 5.9 in L x 2.3 in W x 2.3 in H Dimensions