Traditional undersink RO system with storage tankThe Water Doctor 4-Stage Undersink RO System is a complete drinking water solution for homes that prefer a reliable storage-tank reverse osmosis setup. It includes the core components needed for everyday drinking water, including the RO system, tank and faucet.Best for Households looking for a proven undersink RO setup Customers who prefer a storage tank system over tankless RO Daily drinking, cooking, coffee and tea Homes upgrading from bottled water or basic pitcher filters Key benefits 4-stage reverse osmosis filtration for better-tasting water Storage tank design provides ready-to-use RO water Dedicated drinking water faucet for convenient kitchen use Genuine ROS4A replacement cartridges available for maintenance Practical residential option for many standard kitchens MaintenanceUse Water Doctor ROS4A quick-twist replacement cartridges for routine filter changes. Replacement timing depends on water quality and household usage.Installation noteThis is an undersink RO system. Professional installation is recommended for faucet drilling, tubing setup, drain connection and leak testing.