What is Reverse Osmosis?

Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane to remove ions, molecules, and larger particles from drinking water. It applies pressure to the water on one side of the membrane, forcing it through while leaving contaminants behind. The membrane used in reverse osmosis is designed to allow water molecules to pass through while blocking the passage of larger molecules, ions, and impurities. This process effectively removes many contaminants, including dissolved salts, bacteria, viruses, and other harmful substances, resulting in clean, purified water. Reverse osmosis is commonly used in residential and industrial settings for producing drinking water, seawater desalination, wastewater treatment, and various other applications where high-quality purified water is required.

Residential reverse osmosis (RO) systems work on the same principles as larger industrial RO systems but are scaled down for household use. Here’s how a typical residential reverse osmosis system works:

1. Pre-filtration: Water from the municipal supply or well enters the RO system’s pre-filtration stage. This stage often includes one or more filters to remove sediment, chlorine, and other larger particles that could damage the RO membrane. Common pre-filters include sediment filters and carbon filters.
2. Pressurization: The pre-filtered water then enters a pressurization stage. A pump or the incoming water pressure itself provides the pressure needed to force water through the RO membrane.
3. Reverse Osmosis Membrane: The pressurized water is directed to the reverse osmosis membrane, which is typically a spiral-wound membrane housed in a membrane module. This semipermeable membrane has tiny pores that allow water molecules to pass through while blocking the passage of dissolved salts, minerals, contaminants, and other impurities.
4. Permeate and Reject Streams: As the pressurized water flows through the membrane, it separates into two streams: permeate and concentrate (also called reject). The permeate stream contains purified water molecules that have passed through the membrane, while the concentrate stream contains the concentrated contaminants that were unable to pass through the membrane.
5. Storage and Delivery: The purified water, or permeate, is collected in a storage tank. Most residential RO systems have a small pressurized storage tank to store purified water until it’s needed. When you turn on the faucet, the purified water is delivered from the storage tank through a separate faucet dedicated to the RO system.
6. Waste Water Disposal: The concentrate stream containing the concentrated contaminants is typically discharged or directed to a drain. Some modern residential RO systems may incorporate water-saving features or additional treatment stages to minimize wastewater production.

Overall, residential reverse osmosis systems provide households with a reliable and effective method for producing clean, purified water for drinking, cooking, and other household uses. Regular maintenance, including filter replacements and membrane cleaning, helps ensure the system’s continued efficiency and performance.