Reverse Osmosis Systems

How does reverse osmosis improve drinking water?

Reverse osmosis (RO) reduces dissolved or suspended contaminants in water using pressure to push the unfiltered water, or brine, through a semipermeable membrane. The reverse osmosis membrane blocks the contaminants, allowing the clean water or permeate to flow through to the less concentrated side. RO systems are used in homes and industries where high-quality water with low TDS (total dissolved solids) is required.

A reverse osmosis water system removes:

• Fluoride
• Salt
• Sediment
• Minerals
• Chlorine
• Arsenic
• Volatile organic compounds (VOCs)
• Herbicides
• Pesticides
• Many other dissolved solids

Residential vs. Commercial RO systems

The primary difference between residential and commercial RO systems is water output. Reverse osmosis systems are considered commercial if output exceeds 500 gallons per day (gpd). A commercial reverse osmosis system also uses a specific pressure and larger membrane for greater capacity.

Residential RO systems are point-of-use (POU), designed for installation under a sink in your home or office. Under-sink reverse osmosis systems provide RO water to your faucet and refrigerator. An adapter kit, consisting of a couple of fittings, tubing, and a valve, allows you to run RO water to your refrigerator ice maker or ice machine.

Commercial RO systems are available for high water volume needs, from 200 to 7,000 gallons per day. These systems need greater water pressure to filter water with high concentrations of dissolved solids. Commercial RO systems operate at faster flow rates, Elements like iron, calcium, or magnesium may hinder production or damage the system. Proper steps must be taken to pre-treat the feed water before reverse osmosis filtration to avoid system failure.

Where to use a commercial RO system:

• Seawater desalination
• Car wash rinsing
• Restaurant beverages
• Boiler pre-treatment
• Grocery produce misting
• Ice machines
• Aquarium tanks
• Steamers
• Greenhouses
• Electronics production
• Bottled water
• Maple syrup
• Whole house solutions
• Dairy condensing

Reverse Osmosis Configurations

Quick-Change Filter Cartridges Pros & Cons:

• Easy to replace
• Low profile
• Filter and housing in one
• Greater environmental impact
• Higher maintenance cost

Drop-In Filter Cartridges Pros & Cons:

• No frequent housing replacements
• Less environmental impact
• Less on-going maintenance cost
• Requires special-size filter cartridges

Standard Filter Cartridges Pros & Cons:

• Standard filters and housings easy to find
• No frequent housing replacements
• Less environmental impact
• Lowest on-going maintenance cost
• Larger than other styles
• More involved maintenance

Do I need a 3, 4, or 5 stage RO system?

The number of prefilters or postfilters added to an RO system determine the number of stages. A 4-stage RO system is the best option to filter city supply water entering your home. A 5-stage RO system includes a polishing filter after membrane filtration that gives drinking water one last pass through carbon on the way to the faucet or ice maker to remove tastes, odors, and slime.

What are the parts of a reverse osmosis system?

Air gap faucet: An air-gap faucet helps prevent backflow in a POU reverse osmosis system. If you install an RO system without an air-gap faucet, you will have to create another way to prevent backflow.

Permeate pump: RO system’s efficiency increases if you add a permeate pump. A permeate pump reduces the RO water sent to the drain by 85%.

RO booster pump: A reverse osmosis system runs on home water pressure. Your water pressure may need an extra boost to provide adequate flow from the system to your faucet. An RO booster pump increases water pressure for RO membrane filtration. If your water has TDS over 700 ppm, then you need a booster pump.

Water softener: If you have hard water, you’ll need a water softener to treat it before the reverse osmosis process. Using an RO system to treat hard water will decrease the lifespan of your membrane.

It’s possible for filtered RO water to build up slime, biofilm, and other particles while in the storage tank. You can sanitize your storage tank with the Sani-System kit.

This video explains how to select the best RO system.

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