Boiling Water vs Reverse Osmosis – What’s Better?

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These fancy schmancy RO water filtration systems. Who needs ‘em? Throw 20 dollars down on a kettle, and you will have a cheap and effective water purifier! Am I right?

No. Not right at all. Boiling water has its time and place, but to think it is neutralizing all the contaminants you’re exposed to is quite a stretch.

Let’s compare the two to see if the fancy schmancy RO system is worthwhile or if you should stick with your kettle.

Key Takeaways

  • Both boiling water and reverse osmosis remove pathogens from the water, but that is about as similar as they get.
  • RO water is pretty much free from any contaminants. The same cannot be said about boiled water. Boiling will only kill microorganisms in water, and may evaporate some volatile contaminants – that’s it.
  • The best option for broad-spectrum water filtration is reverse osmosis. If you want to kill pathogens and nothing else, then UV water purification is better than boiling.

Comparison: Boiling Water vs RO Water – Which to Choose?

So, boiling water vs RO water – what’s actually better?

If you are simply looking for a convenient way to kill any pathogens in your water, and maybe reduce some volatile compounds like chlorine, then boiling your water is fine.

Boiling water will kill pathogens and reduce the amount of chlorine in the water, but that is about all it does. In fact, boiling may even increase the concentration of non-volatile compounds in the water, such as lead, and it does nothing to remove contaminants other heavy metals, salts, or chemicals either.

Reverse osmosis, on the other hand, removes almost every water contaminant you can think of, leaving you with nearly 100% pure water.

Under Sink Reverse Osmosis System

The only advantage boiling water may have is if you are doing it purely to kill pathogens. There is a chance with an RO system that it may not be functioning as well as it should, perhaps it hasn’t been maintained properly, or it wasn’t a good quality system. If this is the case, and it isn’t filtering effectively, then boiling water is better for ensuring there are no active pathogens in your drinking water.

What Is Reverse Osmosis Water Purification and How Effective Is It?

Reverse osmosis separates water from contaminants that are dissolved in it. A reverse osmosis system usually includes pre-filtration steps to eliminate chlorine and sediment from the water, before moving through a semipermeable membrane.

The movement of the water through this membrane is the process of reverse osmosis. The membrane has pores so tiny that it doesn’t allow anything bigger than .0001 microns to pass, which is most contaminants. Those left are then discarded with the wastewater.

All in all, an RO membrane can remove up to and more than 99% contamination.

What Does RO Water Purification Remove?

RO filters remove:

  • Microbes
  • Metals
  • VOCs
  • Disinfectants
  • Pesticides
  • Herbicides
  • Minerals and salts
  • Sediment
  • Nitrates/Nitrite
  • Overall Total Dissolved Solids (TDS)

How Effective Is Boiling Water?

Boiling water is highly effective if you want to kill any disease-causing microorganisms in your water. In most cases, bringing your water to a rolling boil for a full minute will effectively kill pathogens.

Boiling water is completely ineffective at contaminant removal, though.

What Does Boiling Water Remove?

Boiling water doesn’t remove things from water. In fact, it can actually concentrate the levels of impurities as it releases steam vapor, leaving the contaminants behind in the boiled water.

Things like arsenic, lead, and fluoride remain in the water, as boiling really only is effective for pathogens and some volatile chemicals including chlorine.

Pros & Cons – Why RO Purified Water Is Better Than Boiled Water and Vice Versa

RO water has a lot of pros but also some cons to consider if you are looking to add one to your home. Boiling water also comes with its own set of advantages and disadvantages. Let’s compare.

Powerful Contaminant Removal

For broad contaminant removal, RO is far superior. While boiling can kill pathogens and eliminate some volatile compounds, it will not remove most other contaminants.

Better Tasting Water

RO removes bad tastes and odors from the water that boiling may not. As RO water is very pure, it has a very neutral flavor.

Simple Installation and Maintenance

Point of use RO systems are straightforward to install and maintain. Boiling water is also easy to set up, but requires you to cool the water before using it.

Wastewater Production

RO systems produce a considerable amount of wastewater, and boiling has hardly any wastewater but is less economical regarding energy consumption.

Water Stripped of All Minerals (Even the Good Ones)

RO water is stripped of all minerals unless a remineralization filter is installed. Boiling water does not do that.

Easy and Convenient

An RO system is easier and more convenient as it either produces water on demand or has a storage tank with filtered water ready to go. Boiling water requires advanced planning to ensure you have cool water for consumption.

Great for Neutralizing Disease Causing Pathogens

Boiling water is excellent for neutralizing disease-causing pathogens. RO water does a great job, but only providing all the filtration components are working effectively, and the feed water has been tested to see if additional filtration components are needed.

Cheap and Low Upfront Costs

Boiling water is relatively cheap, with lower upfront costs than RO, but could get pricey long term due to the electricity output.

Isn’t Suitable for Continuous Treatment

Boiling water can’t be used on demand continuously, like RO water can if you need it for many things.

Boiling water in a pot

Needs to Be Planned in Advance

If you are drinking boiled water, you need to plan in advance to make sure there is always some available that isn’t too hot.

More Expensive Long Term Than UV Purification

Boiling water uses more electricity than RO filtration systems, which could add considerably to your electricity bill if you use large amounts.


Boling water takes a long time, especially if your water kettle is low capacity.

Can Be Dangerous for Scalding or Burning

Boling water is more likely to cause accidents such as scalding or burning, especially in families with children.

Total Dissolved Solids

Boiling will not help to rid your water of total dissolved solids (TDS), whereas RO systems excel at this. Measuring TDS is a great way to determine overall water aesthetics.

Choose Reverse Osmosis in 99% of Cases

In most cases, RO filtration is the better option unless you are only looking for a way to kill microorganisms in your water. Even if that is all you are looking for, a UV water filtration system would be even more effective and convenient.

If you have any questions about boiling water vs reverse osmosis water please don’t hesitate to leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald is one of the founders of BOS and currently head of content creation. She has 8+ years of experience as a water treatment specialist under her belt making her our senior scientist. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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