RO ( reverse osmosis ) Units: Turn off RO system, drain storage tank and remove all filters and membrane. Pour 1 Packet of Sani-System into the empty pre-filter housing. Reconnect and turn on incoming water. After the holding tank is full ( takes about 5 minutes ), let the system stand idle for 60 minutes. Drain Holding tank. Before the system is put back into service, flush the system with water to assure sanitizing solution is rinsed thoroughly from system. Re-Install filters and membrane occurring to manufacturer's instructions.