reverse osmosis

What are the pros and cons of Reverse Osmosis water filters?

Thinking about buying a Reverse Osmosis (RO) water filter? Want to know how RO works? Is there a better alternative? Is it healthy to drink water from a RO filter? In this article we clarify the basics that you need to know about RO filter, the pros and cons and the best alternatives to RO water filters.

What is Reverse Osmosis?

The technology was originally invented as a solution to

  1. Desalinate brackish water or sea water to make it drinkable
  2. Reduce very specific chemical contaminants such as heavy metals

RO is a process through which water pressure pushes the tap water through a semipermeable membrane that allows relatively small water molecules, but not larger molecules such as dissolved minerals (e.g. Salt) to pass through. Thanks to the process the pure tap water is separated from all other substances found in the water. Here's what a typical RO installation looks like along with some of the maintenance requirements. Fast forward to 13:35 to see if RO operation and troubleshooting.

What does Reverse Osmosis filters remove?

RO systems remove contaminants from water including bacteria, viruses, nitrates, sulfates, fluoride, arsenic and much more. But they also removes healthy minerals such as magnesium, calcium, potassium and sodium. Overall RO filters can remove 100s of substances from tap water with a 99% or higher filtration efficiency rate. Some high pressure professional RO filters such as Blue Water even claim 99.9%. Low cost RO filters on the other hand generally have a much lower efficiency. Therefore it's really important that you look at the independent lab tests and certifications of each specific brand and product. RO does not remove chlorine or soften the water very efficiently. Therefore activated carbon filters are almost always required in combination of RO. The activated carbon also helps remove 70+ other contaminants such as pesticides, herbicides, chlorine bi-products, pharmaceuticals and more.

RO filters reduce TDS

"The sales guy used a TDS tester to justify the need for a RO system" TDS measures the amount of dissolved substances in the water. Often the sales technicians use this as an argument for needing a water filter. The problem is that TDS is not a good measurement of clean water. The main components of TDS are typically calcium, magnesium and bicarbonates that the human body needs. A TDS of 250 ppm for example normally just means that the tap water is high in minerals which is good. 

Do I need a RO filter to get clean drinking water at home?

Over the past 10-15 years RO systems combined with activated carbon have been marketed as the only solution for household drinking water. In some cases households can really benefit from a RO filters.

However, for public tap water in Europe and North America RO filters are generally not required. Before purchasing an RO unit or any other water treatment equipment check the quality of your local tap water and what is required to make it safe and tasty. Don't listen to the sales guy.

What are the advantages (pros) of RO filters?

  • Proven technology for pure drinking water and sometimes the only solution
  • High quality filtration for non-potable tap water with e.g. bacteria or heavy metals
  • Can make tap water with extremely high mineral content (TDS of 1500 or higher) drinkable

What are the disadvantages (cons) of RO filtration?

  • Wastes as much as 6x the amount of clean water produced (some products are much more efficient claiming close to zero waste)
  • Requires professional maintenance to ensure effectiveness and safety
  • Water may taste flat and will make coffee and tea taste worse unless water is remineralised
  • Removes healthy minerals including calcium, magnesium, potassium and bicarbonates
  • Relatively expensive starting from €300 ($300) + maintenance and replacements
  • Risk of bacteria growing in the water after the filter since the chlorine has been removed

In 2020 the government of India banned the use of Reverse Osmosis water filters for all water with TDS less than 500 to reduce water and energy waste. Check out our comparison of reverse osmosis vs TAPP water filters.

Is demineralized water from reverse osmosis filters good for you?

It depends on who you ask. According to the World Health Organization, low mineral (TDS) drinking water produced by reverse osmosis or distillation is not suitable for long term human consumption and in fact, can create negative health effects to those consuming it.

This lack of minerals may also impact the taste negatively for many people. With a good diet the minerals from tap water is not critical for you however so therefore drinking demineralised water will not be an issue. Read more about minerals in tap water.

What are the alternatives to RO filters?

Most of the tap water in Europe and North America is already potable (drinkable according to strict WHO, EPA and EU standards). Therefore the first priority is usually improving taste and reducing risk of possible contaminants such as THMs, microplastics and heavy metals. A high quality activated carbon filter will take care of this with the following advantages
  1. Easy to install and replaced by anyone
  2. Cost considerably less
  3. Retains the healthy minerals in the water
  4. Don't waste any water
  5. Lower risk of water going stale / tasting bad

Examples activated carbon filters include TAPP EcoPro. TAPP 2 is an alternative to reverse osmosis filtersFor tap water with bacteria issues there are also affordable ultrafiltration filters such as Ultra by TAPP Water that will remove 99.99% of bacteria and 100+ other contaminants. Other alternatives to reverse osmosis include Ion Exchange, UV purifier, Ozone and distillation. Read more in this water filter guide.

Conclusion about pros and cons of RO Filtration

  • Reverse Osmosis is an amazing technology innovation providing fresh water from sea water in areas around the world where water is a scarcity and for industrial cleaning of contaminated waste water. It can also be a good solution for clean household water when the conditions require.
  • Don't install a RO filter unless you really need it and make sure it's a high quality one to ensure your water is safe to drink
  • For public tap water there are great alternatives including EcoPro by TAPP Water that is simple to install, affordable and sustainable
  • For unsafe public tap water and well water an Ultrafiltration filter such as Ultra by TAPP Water can provide a great alternative

Questions, comments or feedback? Please comment below and we will try to reply within 3-5 days. If you need a faster answer then please e-mail our support on

Disclaimer: Tappwater is owned by Bluewater Group that manufactures the highest quality Superior Osmoss and Reverse Osmosis filters in the world.


How does RO Water filters work (from How Stuff Works)

Disadvantages of RO filters WHO report on Demineralised water Water waste and other disadvantages of Reverse Osmosis


Torna al blog