Reverse Osmosis vs. Distillation

When it comes to water purification, both reverse osmosis filtration and distillation stand out for their effectiveness in removing contaminants from water. However, there are significant differences between these two methods. If you’re considering which to choose for your home, it’s important to know how they stack up against each other.

Let’s take a closer look at reverse osmosis vs. distillation to see which is the better method.

What is Reverse Osmosis?

Reverse osmosis is one of the most thorough ways of purifying water. It’s a filtration system where water is pushed through a semi-permeable membrane in the process of which it leaves behind various contaminants.  Water molecules get through the filter and is clean and safe to drink.

However, unlike other filtration systems, with reverse osmosis the contaminants remain in the water that hasn’t passed through the membrane. This significantly increases the number of contaminants in this unfiltered water, which is why it’s thrown away as wastewater.

For every 3 or 4 gallons of clean water that goes through a reverse osmosis (RO) system, at least one gallon of wastewater needs to be thrown out. This is a waste of water, but on the bright side, RO filters don’t need to be changed as often as other filters.

Reverse osmosis filtration process explained

How Effective is RO?

Reverse osmosis is one of the most thorough filtration methods when it comes to removing contaminants in water. According to the EPA, there are 4 main types of contaminants found in water – physical, radiological, biological and chemical. RO targets most of them.

These contaminants are commonly found in tap and well water, which make the water unpleasant and unsafe to drink. Even water that looks and tastes good can have invisible pollutants within. RO systems are very efficient in getting rid of such pollutants. Here are some:

  • Sediment
  • Salt
  • Chemicals like chlorine, fluoride
  • Pharmaceuticals
  • VOCs (Volatile organic compounds)
  • Heavy metals like arsenic, lead and nickel
  • Pesticides and herbicides
  • Rust and iron
  • Natural minerals like calcium, magnesium and manganese
  • Pathogens like bacteria, viruses, cysts and spores

One thing to note is that while RO systems target biological contaminants, some viruses and bacteria can get through. You may need to use a method of disinfecting water in conjunction with RO to ensure that the water is completely safe.

RO works by purifying water in several stages, which incorporates other types of filters, like carbon block or GAC.

What is Water Distillation?

If you’re familiar with the water cycle, you already have a good idea how distillation works. Distillation works by changing water from liquid to vapor and then condensed. It results in water that is extremely pure. This purity makes distilled water perfect for various uses in the medical and industrial fields as well as for drinking.

To do this, water must be heated until it vaporizes. The vapor is then directed to a container where it’s collected and allowed to condense. Because most contaminants have high melting points compared to water, they can’t vaporize or turn to gas, and so are left behind.

As the water goes through this process, however, it tends to taste flat and flavorless. After all, it’s dead water, with nothing at all in it.

How Effective is Distillation?

This is one of the most effective ways to remove impurities from your water. It may remove more contaminants than RO, but not much more to be considered very significant.

Distilling water is an effective way to remove most of the impurities in the water. These include:

  • Pathogens like bacteria and viruses
  • Heavy metals like lead, arsenic, mercury, copper and iron
  • Minerals like magnesium and calcium
  • Organic and inorganic chemicals
  • Particles
  • Salt
  • Sediment

Additionally, note that some contaminants have a boiling point that’s lower than water, like volatile organic compounds (VOCs). These types of pollutants can get through into distilled water as they also vaporize and condense with the water.

RO vs. Distilled Water – Is There a Difference?

After the above discussion, you might be wondering if there’s a difference between distilled water and RO water. Here’s a look at their similarities and differences:

  • Both these methods purify water effectively and remove almost all the contaminants in them.
  • Both methods effectively get rid of all the minerals in the water, like calcium and magnesium. This results in water that tastes flat.
  • RO will require periodic filter changes, whereas distillers work somewhat like kettles.
  • Neither method is 100% pure because both tend to let some contaminants through.
  • Distillation has numerous applications, including medical and industrial applications like use in batteries and irons. RO, on the other hand, is typically used just for drinking.
  • RO is a more common option for homes than distillers as they use less energy and produces more water.
  • Neither system is suitable for whole-house filtration methods.

RO vs. Distilled Water – No Minerals

Both RO and distilled waters are safe to drink, if you can get past the unappealing flavor of these types of water. However, note that these waters have been demineralized and lack essential nutrients.

Water typically contains minerals like calcium and magnesium that are good for health. Although not significant, this contributes towards your daily mineral intake. Demineralizing removes these nutrients from your water.

This is often blown out of proportion though, because drinking demineralized water won’t make you mineral deficient. There are other more meaningful ways of getting these minerals into your body, like from supplements and a well-balanced diet.

Also, some RO systems like the iSpring RCC7Ak 6-Stage Under-sink Filter include a remineralization stage, which balances out the pH of the water and restores its alkalinity.

Some Other Uses of RO and Distilled Water

Best water for tea

While RO filtered water and distilled water are suitable for drinking, you might want to reconsider if they’ll suit your taste for tea or coffee. In general, it’s best to avoid these ‘flat’ types of water if you don’t want a flat tasting cup of tea or coffee.

However, RO and distilled waters are ideal for house plants as they don’t contain any contaminants that could negatively impact them. Both these types of water have nothing in them that can cause problems for your plants, which is why they’re some of the best types of water for house plants. 

If you’re considering distilled or RO filtered water for aquariums, it’s best avoided unless you know what you’re doing. These waters don’t contain the nutrients that fish are used to and can cause mineral imbalance in the fish. To avoid this, use regular tap water for your aquariums. If you do want to use RO or distilled water, to have a greater control over the pH levels and contaminants in the water, make sure that you supplement the water with the required salts and chemicals before putting the fish in.

RO vs. Distilled Water – Which is Better?

One of the main differences between these two types of water purification methods is that distillation takes a lot more energy than RO systems. Additionally, water distillers don’t have the lifespan of RO systems and parts may need to be replaced frequently.

RO, on the other hand, doesn’t require an energy source to work. The system works with the natural water pressure of the water coming through your pipes. Apart from periodic filter replacements, an RO system has a long lifespan. However, consider that there is a lot of wastewater with RO filters which may not be ideal in dry areas where water sources may be limited. 

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