American Made Reverse Osmosis & Water Filters

There are literally thousands of different water filters on the market today, but we will let you in on a little secret: A vast majority of these filters are the same – they are just branded differently. Now, that doesn’t include what we call “proprietary” filters. Proprietary filters are popular with many of the major brands because they say these filters are engineered for them and they are something special. The truth is – they are made so that no other filter can fit and you have to buy it from the manufacturer – AT A HIGHER PRICE, OF COURSE! That’s called “good business” by some, but we think it’s a bad way to treat customers.

You are always better off if you buy filters that are not proprietary, but rather, “industry standard.” In most cases, the sizes of industry standard filters are as follows:

  • 2-1/2” x 9-7/8” or 10”
  • 2-1/2” x 20”
  • 4-1/2” x 9-7/8” or 10”
  • 4-1/2” x 20”

You can take a tape measure and measure the actual filter (not the filter housing – just the actual filter) to determine the size. Odds are, it is one of those four sizes above. The 2.5” x 10” filters are generally point-of-use filters such as on a reverse osmosis system (although some use them for a whole-house – not recommended), the 2.5” x 20” are for larger reverse osmosis systems and some point-of-entry (whole house filters), while the 4.5” x 10” and 4.5” x 20” are generally all point-of-entry or whole-house filters. The 4.5” filters are also used on commercial reverse osmosis systems.

The sad part about proprietary filters is that they are also most generally manufactured overseas, typically in China or Taiwan. So, not only do they cost more, but they are not made in the USA. Additionally, many of them are much smaller than the industry standard filter. At US Water, our focus is on Made in USA Filters. Sure, we sell some filters that are made overseas, but we don’t hide that fact, and whenever possible, we will sell a USA Made cartridge.

Here’s the best part – our Made in USA filters generally cost a lot less than proprietary filters and less than most competitors’ industry standard filters. If you are ever unsure if your filter is compatible with one of our Made in USA filters, you can e-mail us at, chat with us on the Help Desk or call one of our Certified Water Specialists at 800-608-8792. We are here to help you every day of the year. What type of filter do you need? Here are the different types of filters:

String Filters – String filters are the least expensive filters and while some people like them because they are inexpensive, the fact is that they aren’t very effective at trapping small particulate. The windings on the filter cartridges tend to expand and contract under high flow rates or pressure and they end up letting lots of contaminants get by. Some people say that “string filters last longer.” They certainly do, because they don’t trap as much. They are better than no filter, however. But the question is: Why do you have a filter? Isn’t it to trap contaminants?.

Spun Poly Sediment Filters – Spun Polypropylene or Melt Blown filters are solid filters that have exceptional ability to trap solids using what is called gradient-density layers. Gradient density means that there are differing layers of media which traps larger particles on the outer layer while filter smaller particles on the inner layer.

Our Hydronix Spun Poly filters use a dual gradient density of layers while our US Water Spun Poly Filters use triple gradient density layers. That means that the outer layer might be 10 microns, the second layer is 5 microns and the last layer would be 1 micron. Spun poly filters plug up much quicker than string filters, but do an extremely effective job at stopping silt, sand and sediment, which is why they are the filter of choice in reverse osmosis systems.

Pleated Filters- Pleated filters are extremely popular for whole house filtration as they are very effective at stopping particulates due to the vast amount of surface are they possess. Cheaper pleated filters have fewer pleats and the best pleated filters have nearly double the amount of pleats.

The best pleated filters are not paper, but rather pleated polyester. US Water carries it's own brand of pleated filters that are all made in the USA.

US Water is the best pleated filter and is our best-selling filter. If you have sand, silt, sediment or particulate in your water, a pleated filter is far and away, the best choice.

Carbon Filters - Carbon Filters have been around for decades but recently carbon block technology has become the technology of choice for point-of-use carbon filtration like drinking water filters and reverse osmosis. Carbon block filters use a high-grade of carbon with a large surface area allowing for the greatest use of the carbon's adsorptive capacity. Higher surface area extends the life of the cartridge, lowering the need for frequent filter changes.

There are some applications where a granular activated carbon filter may be used effectively and there are also GAC filters which contain KDF-55 which helps reduce the chlorine before it gets to the carbon, thus increasing the life of the carbon.

A new type of carbon filter is called a Radial Flow Carbon filter which enables a user to achieve flow rates of up to 12 GPM when a 4.5” x 20” housing is used. This is a very cost effective way to reduce the chlorine throughout one’s home.

In-Line Filters - In-line filters are popular as “polishing filters” meaning that they are the final step to filtration processes, such as reverse osmosis. They are also used ahead of icemakers and refrigerators. They generally are carbon filters, but American Companies such as Omnipure make a number of in-line carbon filters that also have polyphosphate (to control scale), Calcite (to raise pH) and other medias for specific applications.

Specialty Filters - There are also a number of American-Made Specialty Filters on our site designed to treat the following contaminants with selective specially media:

Arsenic, fluoride, nitrate and chloramine removal filters are frequently used with reverse osmosis systems to enhance removal of these contaminants.

Reverse Osmosis Filter Packs At US Water, we make it convenient to change your industry standard reverse osmosis filters and to that end, we offer Filter Packs that include US Water Made in America Filters, a sanitizing solution, a syringe to inject the sanitizing solution into the tank, silicone to lubricate the o-rings and full step-by-step directions on how to change your filters. Additionally we have videos with step-by-step instructions on changing your filters HERE. We also offer a full line of Made in USA Reverse Osmosis Membranes.

US Water handles a large selection of replacement filters for both drinking water and whole house applications. For point-of-entry (POE) or whole-house filtration, US Water handles filters manufactured for American Plumber, Ametek, Axeon, Pentek, Flowmatic, Pentair, Watts, Flowmax, Harmsco, Liquatec, WaterBetter, Osmonics , Omnipure and many others. We offer the best prices in the industry for replacement and have our exclusive "Lowest Price Guarantee."

We specialize in Made in America Filters and our Harmsco, Omnipure and US Water filters are all Made Right Here in the U.S.A. Whenever possible, we recommend American Made filters, but unfortuneately, some filter types are just not made in the U.S.A. In that case, we offer only the highest quality replacement filters. We know filters - that's for sure!

If you are not sure what filter fits your needs the best, do not hesitate to call one of our water treatment specialists at 800-608-USWA or e-mail us at