In terms of home water treatment, things rarely get more powerful than reverse osmosis filters. These devices are capable of removing contaminants down to the size of individual water molecules—and when combined in a multi-stage system with other types of filter, can produce water that’s completely clean, safe, and great tasting.

Based on our review process, here are the best whole house reverse osmosis systems available to buy online:

iSpring RCS5T 500 GPD Grade Commercial Tankless Reverse Osmosis RO Water Filter System with 1:1 Drain Ratio, Pressure Gauge
  • 5-STAGE FILTERS: 1-3rd stages remove rust, sand, chlorine, disinfection byproducts and odor. 4th stage Dual-Flow RO Membrane removes heavy metals, pesticide residues, etc. 5th Stage removes chlorine, tastes to improve the quality of drinking water.
  • GREAT CAPACITY: Advanced Dual-Flow 500GPD membrane saves 60% of water, with LOW WASTE 1: 1 drain to clean water ratio. Great for light commercial in Restaurants, Salons, Labs, and Offices all benefit in their ways from high-quality RO water.
  • HIGH EFFICIENCY BOOSTER PUMP: No worries for low water pressure. Built in booster pump increases the production of purified water by raising the water pressure and maximizes RO production rate to the optimal level for the reverse osmosis process.
  • FEATURES: Come with Sliver Chrome drinking water faucet with 360° free swivel and Easy to Read Water Pressure Gauge.
  • EASY-TO-INSTALL AND REPLACE FILTER: Typically, in a couple of hours with industry-leading help just a phone call away with well-organized instructions and videos. Clear see-through 1st stage housing makes filter inspection a snap.
iSpring RCB3P Reverse Osmosis RO Water Filtration System, 300 GPD, Tankless, for Residential and Light Commercial usage,TDS Reduction, with Booster Pump and Pressure Gauge
  • High capacity Reverse Osmosis systems removes up to 99% of over 1, 000 contaminants and hardness, including lead (removes up to 98% of lead), chlorine, fluoride, arsenic, asbestos, calcium, sodium and more.
  • Freestanding Stainless Steel Frame and Metal hanging bracket. Makes your installation and filter changes easier while adding a protective buffer for your system
  • Super-efficient RO membranes combine to provide up to 300 gallons of purified reverse osmosis water daily. Rejects wide spectrum of impurities down to .0001 micron.
  • Built in booster pump increases the production of purified water by raising the water pressure. Compatible with 11 or 20 gallon iSpring storage tank. TANK NOT INCLUDED.
  • Great for light commercial use in Restaurants, salons, labs, and offices all benefit in their own ways from high quality RO water.

How does Reverse Osmosis work, exactly?

Reverse osmosis (RO) is the opposite of osmosis. This is the natural flow of water from solutions of a lower concentration to a higher concentration. Left alone, water divided by a semipermeable membrane will travel in the direction of the most solutes, until the entire water system is equally concentrated.

By applying pressure to a water source—either through a pressure tank or simply the wider system pressure—reverse osmosis systems push water through a membrane in the opposite direction. That is, from an area of more to less concentration. The membranes used in a RO filter can have pores as small as 0.0005 microns, which is basically the minimum size through which water itself can pass.

As a result, any contaminant of equal or larger size than water molecules should be caught by the RO membrane. This includes sediments, bacteria, asbestos, lead, and other heavy metals. Some common drinking water contaminants do have a smaller molecule size than water, and can therefore make it through the membrane. Chlorine, for example, as well as some other organic chemicals, are not filterable by RO.

For this reason, it’s common for reverse osmosis systems to include a carbon filtering stage, to take care of any leftover materials. A pre-filtering screen can also extend the lifespan of a filter system, by removing large particles before they reach the more delicate RO membrane.

WECO HydroSense Light Commercial Reverse Osmosis Water Filter System (HydroSense-0500)
  • Reverse osmosis drinking water purification system for residential and light commercial applications
  • Sediment and compressed carbon block pre-filtration removes tiny particles like rust, silt, taste and odor-causing chemicals like chlorine, chloramine and rotten-egg odors.
  • Standard 1812 Volume Thin Film Composite reverse osmosis membrans removes up to 98.5% of water contaminants like nitrate, TDS, fluoride, lead, sodium and mercury.
  • Ideal for residential drinking water use, medical offices, laboratories, schools, aquariums and hydroponic growing operations. Automated water pressure sensors and booster pumps keep system functioning at maximum capacity.
  • Please note this is not a complete whole house reverse osmosis system. Atmospheric tanks, jet pumps and other equipment need to be purchased separately for turning this system into a part of whole house RO setup. Read our whole house RO setup blog and contact us for more information before purchasing for whole house applications.

Point of use (POU) Vs Point of entry (POE)

Whole-house reverse osmosis systems are installed at the earliest point in a building’s plumbing, either where the mains water supply enters a house, or after the pressure tank of a private well.

This makes them a point-of-entry or POE system. These filters provide the ultimate peace of mind for home water treatment, ensuring that anything drawing water inside your home, be it sinks, showers, dishwashers, or laundry machines, is accessing pre-filtered water.

Despite this benefit, some find that smaller, point-of-use or POU systems better fit their needs. Only filtering water at specific outlets—the kitchen faucet, for example—reduces the cost of filter components, as well as lowering the possibility of reduced water flow, which can come with some POE filter systems.