Does Reverse Osmosis Remove Bacteria?

✅ Our content is written by humans, not AI robots. Learn More

No matter what your reasons for needing to remove bacteria from water, if you’re researching your options, you’re probably wondering about the efficacy of reverse osmosis. As one of the most popular and thorough water treatment solutions, this type of filtration clearly has a lot going for it – but will reverse osmosis remove bacteria?

The answer to that question is yes – but how can you be sure that it’s the best bacteria removal method for you? I’ll share all the information you need to know in this guide.

How Does Reverse Osmosis Remove Bacteria?

Reverse osmosis systems send water through several stages of filtration. Water passes through a series of filters, including a carbon filter, a sediment filter and a post-filter. If you know anything about water treatment, however, you’ll know that the average filter can’t handle bacteria. Most filters have a pore size of between 1 micron and 5 microns – and considering bacteria is smaller than this, it can simply slip through the cracks with the water molecules.

What makes reverse osmosis systems different is that, once your water supply has been filtered, it’ll then be sent through a semi-permeable membrane. This membrane has tiny pores of around 0.0001 microns, so it can effectively act as a sieve, blocking pretty much every contaminant of every size. Because this membrane has such a tiny pore size, not even tiny bacteria can pass through. Only water molecules can get to the other side, while bacteria (like salmonella) and viruses (like hepatitis) are flushed down a drain with wastewater.

Don’t be mistaken – RO technology can’t kill bacteria or viruses. It simply ensures they’re filtered out, so you end up with fully pure water. If you’re looking for something that’ll kill these microorganisms, you’re best looking at UV treatment.

Membrane Filtration Process

How Much Bacteria Does RO Remove?

Reverse osmosis has a high level of effectiveness when it comes to removing bacteria and viruses from drinking water. These contaminants are known as organic material, and a good reverse osmosis filtration system is capable of removing bacteria up 99.9% effectiveness. Common examples of the types of bacteria and viruses that reverse osmosis can remove are Campylobacter, Shigella, E. coli, Salmonella, Hepatitis A, Rotavirus, and Norovirus.

does ro remove bacteria

Other Contaminants Reverse Osmosis Water Filters Remove

Aside from organic material, reverse osmosis systems can also remove a whole host of contaminants from a drinking water supply. In fact, the RO membrane is effective enough to filter up to 99.99% of all TDS (total dissolved solids) in water.

Some of the contaminants removed by an RO system include chemicals such as chlorine, heavy metals such as lead, hardness minerals such as calcium and magnesium, and other chemical and organic impurities that could affect our health, including fluoride, radium, nitrate, and potassium.

Disadvantages of Reverse Osmosis Systems

Healthy Stuff Also Removed

One of the biggest setbacks of reverse osmosis is that it’s almost too effective – the system removes the good stuff, such as various healthy minerals from water, too. While we get many of these minerals in abundance from food sources, you may still like the idea of getting a little extra from your drinking water source. Some people also think that water containing no minerals has a “flat” or “boring” taste. You can add some minerals back to your water, but it’d be better if they weren’t filtered out in the first place.

Creates Wastewater

Though the effectiveness of reverse osmosis filtration can’t be argued, the system’s efficiency doesn’t match up. The nature of a reverse osmosis system is that it wastes water as it produces clean water; the average wastewater to pure water ratio is 4:1. This means a large portion of your water won’t actually make its way out of your tap. Instead, it’ll be washed away. Water waste has to happen during RO, or there would be a build-up of contaminants in the RO chamber that could damage the membrane. When water is flushed away, it takes the contaminants with it.

Hefty Price Tag

Because the reverse osmosis experience is considered the best way of removing everything from chlorine chemicals to viruses and bacteria, it’s unsurprising that it comes at a cost. You’ll often need to pay upwards of $400 minimum for a system for under-sink or whole-home use.

Requires Maintenance

Take note, too, that after you’ve installed a reverse osmosis system, it’ll need maintenance. The exact maintenance in question depends on the unit you’ve opted for, and whether it’s a small system installed at your faucet or a larger unit installed at your home’s point of entry. Typically, you’ll need to change the filter cartridges once every 6 to 12 months or so, and the RO membrane once every 2 years. Maintenance is an important and unavoidable aspect of owning this type of water treatment solution.

Considerations for Choosing an RO System

System type

There are several different categories of RO systems found on today’s market, so it’s worth posing the question of what you’re looking for in your search. Yes, under-sink tap water units are the most popular, but if you want to get safe, clean water for your whole home, you may want to consider a point of entry system.

Many countertop RO products have also taken off in recent years. These systems work well as a more portable solution – these can be useful for people living in rental properties.

Your Budget

At the very least, you’ll need to budget at least $300 for a reverse osmosis unit. Some systems can cost closer to $1,000 or more. The upfront purchase is the biggest cost, but don’t forget to save some cash to order your yearly filter replacements, which are usually more affordable at $30-$60 per pack.

Efficiency Ratio

As I mentioned earlier, the typical RO efficiency ratio is 4 gallons of wastewater to 1 gallon of pure water produced. But in recent years, manufacturers have set to work on providing more efficient systems with wastewater to pure water ratios of 3:1, 2:1 and even 1:1. Though these units tend to cost more money upfront, the savings you get with long-term use in the end might make it a worthwhile investment for you over time.

Your Water Quality

The quality of your water is also something to consider in your search, as it may affect the efficiency of your RO system. A high contaminant level will likely affect the filtering process and will result in shorter filter and membrane lifespans. However, if your water pressure is high enough, your water’s quality shouldn’t affect the speed of filtration.

Additional UV Addon

While RO is capable of removing the majority of bacteria and viruses, using a UV light can help offer that extra reassurance if your water source is high in these contaminants. A UV add-on is a chemical-free solution that’ll ensure your water is 100% safe to drink, as its treatment process involves killing pathogens, rather than removing them.

About The Author

Scroll to Top