• Test water for purity (TDS test)
• Test automatic shut-off
• Test good water production rate
• Test flow restrictor
• Test check valve if indicated
• Test water safety valve
• Test house pressure
• Clean and lubricate o-rings
• Service holding tank
• Replace filters, membrane when indicated, other parts as needed

Check valve, flow restrictor, and automatic shut-off and holding tank must all be working as designed for any home reverse osmosis system to function properly.