Western Industrial has supplied Replacement Parts for Reverse Osmosis Commercial Water Purification Systems for 30 years

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UV Lamps

We carry arc tubes, UV lamps, quartz sleeves and parts for Aquionics, Hanovia and Berson UV-techneik systems.


We carry Dow/Filmtec, Hydranautics, Osmonics, Desal, Koch, Toray and TriSep replacement RO membranes.


We carry filters for microfiltration, ultrafiltration and nanofiltration specifications from several suppliers.

Need Help?

In-stock items usually ship the same day. If we don't have some obscure part in stock, we'll try to track one down for you.

Valves / Pumps / Motors

Whether you need valves, pumps, motors, gauges or any manner of replacement parts, you want us to be your first call.

Woman-Owned Small Business

Wendy Quinn started her water filtration parts business in 1986 with an initial focus on the semiconductor industry.

How Reverse Osmosis Membranes Work

Reverse osmosis water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for its intended use, most commonly human consumption. RO water treatment equipment is often used at pure and mineral water plants, bottled water and beverage processing plants.

Reverse Osmosis Process

Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, minerals such as iron, manganese and sulfur, and man-made chemical pollutants such as fertilizers.

Reverse Osmosis Instructional Video

Graphic visualization of an industrial reverse osmosis system with twelve RO pressure vessels first pass and five RO pressure vessels for the second pass, totalling seventeen reverse osmosis pressure vessels within a water treatment, filtering and purification installation.

Changing Reverse Osmosis Membranes by Hand

Replacing RO membrane cartridges in large scale systems is clearly a two-person job but it seems simple enough. Grab, twist, push and repeat. Mind you, we ask that you follow your specific product installation procedure guidelines as they may vary between each manufacturer.

How Reverse Osmosis Membranes are Made

While we only supply the finished product, we thought you might be interested in seeing just how the reverse osmosis products we sell are made. Please note that this is merely an example and does not reflect the large scale manufacturing capabilities of our major suppliers.

Reverse Osmosis Membranes Simplified

Kinetico Home Water Systems, a manufacturer of residential reverse osmosis water treatment systems, produced this entertaining video that explains the RO process through animation.

Industrial Reverse Osmosis Membrane Systems

An explanation of the basic concepts of reverse osmosis including pretreatment through particulate and carbon filtration showing the difference between osmosis and reverse osmosis as well as how to store and distribute the RO product water to the points of use through ultraviolet disinfection, mixed bed deionization and final filtration.

The Science Behind Reverse Osmosis

Osmosis is a special case of diffusion (molecule movement) in which the molecules are water and the concentration gradient occurs across a semi-permeable membrane. To illustrate, imagine a semi-permeable membrane with fresh water on one side and a concentrated aqueous solution like sea water on the other side. If normal osmosis takes place, the fresh water will wish to cross the membrane to dilute the concentrated solution until equilibrium is reached.

Reverse osmosis is the opposite of the natural osmotic process, where water from a solution with a low concentration of dissolved solids travels through a membrane seeking to dilute a higher concentration solution. A reverse osmosis water system applies pressure with a pump to a solution with a high concentration of dissolved solids, causing water from the concentrated solution to pass through the membrane to the fresh water side.

The first practical reverse osmosis (RO) membrane was invented in 1959 by Loeb and Sourirajan at the University of California, Los Angeles.

Now there are at least seven major manufacturers of RO membranes in the world, even more that make their own nanofiltraton and ultrafiltration membranes, and numerous other companies that buy membrane sheet for the purpose of fabricating commodity-type membrane elements.

The driving force for the development and use of RO membranes is the advantages that these have over traditional separation processes such as distillation, extraction, ion exchange, and adsorption.

Reverse osmosis is a pressure-driven process so no energy-intensive phase changes or potentially expensive solvents or adsorbents are needed for RO separations.

Reverse osmosis is a process that is inherently simple to design and operate compared to many traditional separation processes.  Also, simultaneous separation and concentration of both inorganic and organic compounds is possible with the RO process.

Depending on the membrane specifications, reverse osmosis water treatment systems have a very high effectiveness in removing protozoa (ie. Cryptosporidium, Giardia); bacteria (ie. Campylobacter, Salmonella, Shigella, E. coli); viruses (ie. Enteric, Hepatitis A, Norovirus, Rotavirus); and will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead. They may also reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.

Reverse osmosis is typically used for boiler feed/makeup water, ice making, laboratories, manufacturing process water, metal finishing, pharmaceutics, chemical process water, cosmetics, drinking water, electronics, food and beverage processing, horticulture, humidification, photographic processing, printing, and vehicle washes.

Finally, reverse osmosis technology can also be combined with ultrafiltration, pervaporation, distillation, and other separation techniques to produce hybrid processes that result in highly efficient and selective separations (Bhattacharyya et al., 1992).

With nanofiltration ("loose RO") membranes selective solute separations based on charge and molecular weight/size differences are possible.

Semi-permeable refers to a membrane that selectively allows certain things to pass through it while retaining others. The membrane allows the passage of water, but not ions (ie. Na+, Ca2+, Cl-) or larger molecules (ie. glucose, urea, bacteria). Unwanted particles generally pass through the membrane slower than the water. In salt water RO, for example, the solvent (water) passes through the membrane at a much faster rate than the dissolved solids (salts). The net effect is that a solute-solvent separation occurs, with pure water being the product.

Some of our water filtration parts suppliers

Get in touch with Western Industrial Inc

Your commercial water system parts supplier

Please contact us whenever you need spare replacement parts for any type of water purification system. We ship worldwide with the exception of high fraud risk countries. Our California office is open Monday through Friday from 8:00am to 5:00pm Pacific Standard Time but you can write to us anytime and we'll get back to you as soon as possible, often after-hours, because emergencies happen.

One of our goals is to continue to offer our customers the most up-to-date water treatment equipment and technology. So, if you are a water treatment component manufacturer looking for an established parts and consumables distributor for your product line, give us a call. We'd love to hear from you.

  • PO Box 1958, 7395 Starr Road, Windsor, CA 95492
  • (707) 838-8078
  • Toll free: (800) 348-4222