Contest: Common Home Drinking Water Treatment Technologies Compared

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In today’s blog post, we are going to start a contest and compare the most common home drinking water treatment technologies to one another. Thereby, we are going to rate each technology from 1 to 5 stars in the following categories:

  1. Provided Degree of Water Purity
  2. Required Time for Purification
  3. Amount of Water Wasted
  4. Energy Efficiency
  5. Overall Rating

Furthermore, we will also weigh in important advantages and disadvantages and in the end hopefully be able to pronounce a clear winner.

Common Home Drinking Water Treatment Technologies

Reverse Osmosis

Since this website is called, we are going to start, of course, with taking a quick look at reverse osmosis filtration.

RO systems have the advantage that they not only apply a semipermeable membrane for the reverse osmosis process, they also come with additional pre and post-filters.

First of all and most importantly, reverse osmosis systems provide exceptionally pure water. According to manufacturers, the average model is able to remove between 98 and 99% of all impurities including larger particles, organic molecules and most viruses.

Reverse Osmosis Process Diagram

Depending on water pressure, the filtration process is fast. Also, most systems come with a storage tank so you don’t have to wait for purified water being produced on demand.

About 3 to 5 gallons of water are wasted for every gallon of filtered water, if you are not using a booster pump. Compared to other technologies, RO systems aren’t performing quite as well here. Then again, in terms of energy efficiency, they can’t be beaten, as they rely on water pressure alone and don’t require a power source.

  1. Provided Degree of Water Purity – 5 Stars
  2. Required Time for Purification – 4.5 Stars
  3. Amount of Water Wasted – 2.5 Stars
  4. Energy Efficiency – 5 Stars
  5. Overall Rating – 4.5 Stars


Next, we are going to take a look at water distillation systems. Distillers heat water to the boiling point and collect the condensed vapor that has left almost 100% of all contaminants behind. They are very effective in

  • eliminating protozoa (e.g. Cryptosporidium, Giardia),
  • eliminating bacteria (e.g. Campylobacter, Salmonella, Shigella, E. coli),
  • eliminating viruses (e.g. Enteric, Hepatitis A, Norovirus, Rotavirus)

and also remove organic and inorganic contaminants such as arsenic, cadmium, lead, nitrate and sulfate (source).

2 obvious drawbacks of distillers are their lengthy purification process – you have to wait for hours to get enough clean water – and the high amount of energy that’s needed for boiling. On the other hand, wastewater production is close to zero!

  1. Provided Degree of Water Purity – 5 Stars
  2. Required Time for Purification – 2.5 Stars
  3. Amount of Water Wasted – 5 Stars
  4. Energy Efficiency – 2 Stars
  5. Overall Rating – 3.5 Stars

UV Light Treatment

As the name suggests, UV light treatment systems use ultraviolet light to disinfect water. They have a very high effectiveness in

  • killing protozoa (e.g. Cryptosporidium, Giardia),
  • killing bacteria (e.g. Campylobacter, Salmonella, Shigella, E. coli)

and a high effectiveness in

  • killing viruses (e.g. Enteric, Hepatitis A, Norovirus, Rotavirus).

UV lamp

Their only drawback: They don’t remove any substances from water at all. They reduce neither chemical content, nor heavy metals or salts etc.

The time that a UV treatment system requires for disinfection is a mere seconds. Plus no water is being wasted during the process and the energy efficiency is good.

  1. Provided Degree of Water Purity – 2 Stars
  2. Required Time for Purification – 5 Stars
  3. Amount of Water Wasted – 5 Stars
  4. Energy Efficiency – 4 Stars
  5. Overall Rating – 4 Stars

Micro, Ultra & Nanofiltration

The chart below shows pore size and effectiveness (E) in removing protozoa, bacteria, viruses and chemicals for micro, ultra and nanofiltration.

Pore SizeE Removing ProtozoaE Removing BacteriaE Removing VirusesE Removing Chemicals
Microfilt.0.05 – 5 micronVery highModerateNoneNone
Ultrafilt.0.001 – 0.05 micronVery highVery highModerateLow
Nanofilt.0.008 – 0.01 micronVery highVery highVery highModerate

As the chart shows, neither microfiltration and ultrafiltration nor nanofiltration are really suited for removing chemicals out of our drinking water. Above that, microfiltration is not suited for removing bacteria and viruses either.

Ultrafiltration is very effective in removing bacteria from water, but only moderately effective in removing viruses. Nanofiltration is the only technology that is able to filter out both bacteria and viruses to provide water safe for human consumption.

As far as purification speed is concerned, it’s not really possible to determine how long it takes to treat water by micro, ultra or nanofiltration – there are different ways to apply the technology. The same goes for energy efficiency. On the upside, little to no water is wasted.

  1. Provided Degree of Water Purity – 4.0 Stars
  2. Required Time for Purification – ?
  3. Amount of Water Wasted – 5 Stars
  4. Energy Efficiency – ?
  5. Overall Rating – ?

Water Softening

It’s quite simple: Commercial water softeners are neither intended nor suited for the production of drinking water. Their sole purpose is to reduce hardness to protect your household appliances and plumbing system from clogging.

Our Winner: Reverse Osmosis


And the winner of our contest for the best home drinking water treatment technology is… Reverse Osmosis – congratulations!

Reverse osmosis provides very clean water with no need for an extra power source. The filtration process is quick and most systems come with a tank to store water for later use. The only drawback is that during the treatment process a lot of water is being wasted.

By the way, other treatment technologies can be used in conjunction with reverse osmosis to achieve even higher water purity levels. Right now, a combination of reverse osmosis with carbon pre-filters + UV-light treatment is the best the industry has to offer.

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Questions? Don’t hesitate to ask – just leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald has been with BOS since the very beginning. She is head of content creation and has fully immersed herself into the home water treatment industry only to become an expert herself. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
Learn more about Gene and the rest of the BOS Team.


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