Are you lost, confused, afraid? Have you found yourself scouring the internet getting sucked into hours of DIY youtube videos? Are you looking at your reverse osmosis filtration system like it’s an untrained emergency tracheotomy on a turbulent plane? Fear not! This article is for you.
“I have an Omnipure filter system and I need to replace the filters but I don’t know what I’m looking for, or how to do it?” We must receive this call at least 6 times a day most days. The shocker is that Omnipure doesn’t actually produce any complete systems.

We make filters yes, but in most cases our filters are used as components in complete systems made up of different parts and brands. Before we dive too deep let’s look at an “average” 5 stage system and learn some of the parts. Keep in mind that RO systems come in many different shapes and sizes but the way they work is generally the same.

  1. Sediment pre filter housing.
  2. Carbon pre filter housing.
  3. Carbon pre filter housing.
  4. RO membrane.
  5. Carbon post filter.

The first stage, or (A) is all about removing any larger sediment particles from the water. Dirt, sand, or George Washington’s wooden teeth are no match for this simple fibrous filter. Wondering how that got in there? Anyone who’s been to the beach can tell you, sand can get into anywhere.



The second and third stages, or (B) and (C) pass the water through carbon filters. This removes many contaminants but most importantly it removes chlorine. This is vital because chlorine degrades many RO membranes leading to fouling or plugging. Omnipure carbon blocks work great in these stages (shameless product plug… check). Simply disconnect the housings, (stage B & C) pull out the old carbon element and insert the new Omnipure carbon block element.

Stage four, or (D) is the Reverse osmosis membrane. This is as they say, is where the magic happens. Filtered water is forced via your house water pressure through a semipermeable membrane. The pores of the membrane are so small that nearly everything besides the water molecule is too big to pass through. When it comes out the other side you have super clean RO water. All the left over stuff is rinsed off the membrane and pushed out of a drain line into your main drain. The clean water moves to the storage tank until you need it.

Stage five, or (E) is the carbon post filter. It usually sits atop everything else and is the last filtration step before the water goes to the faucet. This final step “polishes” the water to remove any taste, color, or odor it picked up in the tank. It is also the first label people notice, hence why we receive so many calls. Our K-series and CL-series are widely used as post polishing filters.

Holding all these parts together is the manifold. If your system has a brand name it would be here. Many systems are generic, allowing for personalization based on your water quality needs. For the most part regular replacement of the filters is all the maintenance you need, however other parts may wear out. Common parts that need replacement are the housing o-rings, and filter fittings (the parts the water line plugs into.) Now that we know what we are looking at we can go over a few do’s and don’ts of replacing your water filters.

  • Do… shut off your water to the system. Unless your kitchen can float make sure your water is off before you start taking stuff apart.
  • Don’t… skip that step. Seriously, water damage is no fun.
  • Do… take notes on how everything is hooked up. A couple pictures could help as well.
  • Don’t… wait too long to replace your filters. Replacing filters per manufacturer instruction keeps your system working well and water tasting great.
  • Do… invest in proper tools. A filter wrench can save a big donation to the curse jar.
  • Don’t… hesitate to call a water professional if things go wrong. They will have you fixed up in a jiff.  

Hopefully you know a little more than you used to, and looking at your RO system is a little less terrifying.  Need to get some filters? Take a look at our distributors here (link to distributors map) Stay safe, stay hydrated.

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