Reverse Osmosis FAQs


Before taking the plunge and buying a new water filter, it’s important that you know exactly what lies ahead. We’ve compiled a list of common questions people have about reverse osmosis water filter systems. We’ll add to this regularly, and hope it can be of use. If we can’t answer your questions here, then please leave a comment.

  1. How effective is reverse osmosis technology?  It is currently the most effective water filtration method available. This technology is used to produce bottled water.
  2. How should I choose which model to get?  The most important consideration should be the household water pressure. Each model is designed with low, very low or regular water pressure levels in mind. Those with low water pressure levels (below 40 psi) will require a pump to be included in their system.
  3. Can I install my reverse osmosis water filter system?  Most systems are very straight forward to install. This installation video is very informative, and most systems follow this routine closely.
  4. Where can we install the system? Most RO systems are designed to be installed under the kitchen sink. They can also be installed in the basement or garage if need be. The water pressure would have to be good, or a pump would be needed though.
  5. If we move can we take the system with us?  Yes, RO systems are easy to uninstall. Manufacturers offer a ‘Move-kit‘ to aid re-installation.
  6. Can I connect the RO system to my ice maker  Yes, using a 1/4″ tube.
  7. How long will it last?  If it is well serviced and parts are replaced in good time then virtually forever. The typical life span of the membrane is 2-5 years (depends on the initial water quality). The filters should be replaced every 6-12 months. These figures vary from company to company.
  8. Will it affect the mineral content of my water?  A reverse osmosis system cannot distinguish between good minerals and bad impurities, so it will affect the mineral content of your water. It will remove around 90-99% of impurities though. An alkaline or calcite filter can be used to add the minerals back at the end of the process.
  9. Will it affect the PH of my drinking water?  By removing some minerals then yes it will make the water slightly more acidic. An alkaline filter can be included with most RO systems that will improve the pH of the filtered water and return it to more natural, alkaline pH levels.
  10. Does a reverse osmosis filter need electricity?  No, they use water pressure.
  11. Will a water softener affect the RO filter?  No, a water softener will actually extend the life of the membrane. By softening the water it helps to protect the RO unit.
  12. I’ve heard reverse osmosis system waste a lot of water. How much do they typically waste? Leading brands such as iSpring and APEC typically waste around 2 or 3 gallons of water for every gallon of drinking water. These figures can be improved by situating your RO system on the counter-top instead of under the sink, and also be using a pump (can be included at extra cost). With the addition of a pump, the waste water to drinking water ratio can reach around 1:1.

To see how different RO systems compare, please read our complete guide to reverse osmosis.

See how an RO system works, piece by piece here.

Discover the history of reverse osmosis filtration in this post.

Hi I'm Jamie, teacher and owner/chief contributor at We strive to bring you the most informative water filter reviews in the most intuitive and user friendly way. Besides offering advice on the water filter to suit your needs, we also post topical articles on water pollution and the environment. Stay connected and follow us on, Facebook, Twitter, Google+ and more!

  1. Your FAQ just helps me a lot about osmosis. Thank you!

  2. if ro systems waste’s 2 to 3 gallons of water for every 1 gallon of drinkable water.. then which is an effective method to filter water ?… does the waste water go down the drainage ? Do we have other alternatives to filter water at a domestic / household level ?

  3. Terrific post however , I was wanting to know if you could write a litte more
    on this topic? I’d be very grateful if you could elaborate
    a little bit further. Bless you!

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