Under Sink Reverse Osmosis Water Filters


Under Sink Reverse Osmosis & Ultrafiltration systems have 12 to 17 stages - the number varying with model and options of Reverse Osmosis/Ultrafiltration Systems. Crystal Quest Reverse Osmosis/Ultrafiltration systems produce up to 100 gallons of top quality water per day and remove up to 99.9% of undesirable contaminants and filter particles as small as 1/10,000 of a micron by forcing untreated water through a semi-permeable membrane. Pressure forces the water to flow in the reverse direction to the direction of flow in natural osmosis. View our Comparison Chart of all Under Sink Reverse Osmosis THUNDER® Systems.


Crystal Quest® Reverse Osmosis and Ultrafiltration systems are a revolutionary breakthrough in the reverse osmosis and ultrafiltration industry. Through years of experience and research we have produced a totally new, healthier and more effective Reverse Osmosis/Ultrafiltration system in the market today. Simply, the best under sink reverse osmosis systems available.

Crystal Quest Reverse Osmosis/Ultrafiltration systems have compact designs that can easily fit beneath any kitchen or bathroom sink. Supplied with a complete installation kit that includes a European lead-free long-reach designer faucet.

Our Reverse Osmosis Systems use the most advanced membrane technology to produce permeate (excellent) water without odor or taste. Learn more about our Reverse Osmosis Membrane. Permeate water may be acidic (low or absence of mineral content). For healthy drinking water, remineralization is recommended. 


The Thunder C Series uses a 3-stage Granulated Activated Coconut Shell Carbon (GAC) Filter Cartridge & post membrane cartridge, to remove volatile organic carbon compounds (VOC’s), insecticides, pesticides and industrial solvents.

Buy a C Series Replacement Cartridge.


The Thunder M Series uses a 6-stage Filtration Cartridge, pre one-micron filter pad, RO membrane cartridge, ERA-6500®, ERA-9500®, GAC (coconut shell), ceramic ball resin, and post one-micron pad. 

Buy a M Series Replacement Cartridge.


P Models include a pressure pump. Please consider these models if you have low water pressure.

View our Comparison Chart of all Under Sink Reverse Osmosis THUNDER® Systems.

To inquire about the right water filtration system for you, please email help@crystalquest.com or call 1-800-934-0051

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Customer Service
M-F 9am - 5pm EST (800) 934-0051 or (770) 951-5600
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