TM 10-6640-215-13 2-8. OPERATING PROCEDURES -continued. (e)   Secure opposite end of hose to pressurized water source. (f) In the mechanical room, position the water system valves as follows: 1 Input valve to pre filter - OPEN 2 Input valve post filter - OPEN 3 Pump suction or tank fill directional flow valve - OPEN to Tank Fill 4 Tank fill or water system - OPEN to System Input directional flow valve 5 Water tank drain valve - CLOSED 6 Pump suction valve from water   - CLOSED tank 7 Water system drain - CLOSED valve and petcocks (3) 8 Main water valve from pump - CLOSED (g)   Slowly turn on water supply at source. (h)   Open sink faucet and purge air from system. (i) When a solid stream of water flows from faucet, close faucet and check system for leaks. (4)   Operate the Water System Using an Outside Unpressurized Source. (a)   Unlatch and open UTILITIES box door. (b)   Connect garden hose adapter to water system connector. (c)   Attach 50-foot (15.25 m) garden hose to adapter. (d)   Position water inlet/outlet selection valve to the IN position. (e)   Secure opposite end of hose to unpressurized water source. (f) In mechanical room, position the water system valves as follows (see Figure 2-19): 1 Input valve to pre filter - OPEN 2 Input valve post filter - OPEN 3 Pump suction or tank fill directional flow valve - OPEN to Pump Suction 2-52