Does Reverse Osmosis Remove Odor from Drinking Water?

Does Reverse Osmosis Remove Odor from Drinking Water?

If you have noticed a bad smell coming from your drinking water, you may be wondering if reverse osmosis can help remove it.

Reverse osmosis systems can remove most odors from drinking water. The removal efficiency depends on what the odor is and its cause. RO can remove the chemical smell caused by chlorine or a rotten egg odor from hydrogen sulfide. In both cases, it is the carbon pre-filter that removes the source of odor in water and not the reverse osmosis membrane.

In this blog post, we will answer that question and give you some tips on how to improve the odor of your drinking water. Keep reading to learn more!

Odors in Drinking Water

The water in the United States is quite safe to drink. Although municipalities test, treat, and closely monitor tap water quality, sometimes the water can have a bad taste or smell. Knowing what’s causing your water to smell bad is the first step in solving the problem.

What can make your water smell bad

There are a few common culprits that can make your water smell bad:

  1. Chlorine added for disinfection: Chlorine is added to most tap water in order to kill bacteria, viruses, and other microbes. The residual disinfectant has a strong chemical odor that many people say smells like a swimming pool.
  2. Sulfur in the ground: Many parts of the United States have high levels of sulfur in the ground. Sulfur-reducing bacteria convert this inorganic sulfur to hydrogen sulfide gas, which gives water a distinct rotten egg smell.

Is it safe to drink water that smells bad?

If your water has a bad test or odor, you’re probably wondering if it’s safe to drink. Yes, in most situations. However, let’s look at each issue to see if you should be concerned about your health.

Here are the most common odor complaints people have with their tap water.

  1. Chemical or chlorine taste: Residual chlorine or byproducts from disinfection are to blame. Although these compounds are present in your water, the EPA has stated that the residual levels of chlorine are safe.
  2. Sulfur or rotten eggs: The rotten egg smell in your water is caused by hydrogen sulfide. Although this water smells bad, it is still safe to drink.

Reverse Osmosisreverse osmosis filter system

Reverse osmosis is a widely used treatment method that reliably removes a wide range of contaminants from drinking water. It is effective at reducing the concentration of many impurities such as lead, PFAS, and heavy metals.

How RO works

Reverse osmosis systems use a semipermeable membrane to filter impurities from water. The membrane allows water to flow through while trapping dissolved solids and other contaminants. The system applies pressure to the water, forcing it through the membrane and removing any impurities.

The membrane is constructed of a semi-permeable polymer that is spirally wrapped around a central tube. The water is forced through the membrane, and the impurities are filtered out. The clean water is then collected on the other side of the membrane, while the contaminants are retained in a concentrated brine. This brine waste is then flushed down the drain.

Reverse osmosis systems can be used to treat both municipal water supplies and private wells. This treatment technology is effective at removing a wide range of contaminants, including salt, bacteria, viruses, pesticides, and more.

RO system components

Reverse osmosis systems typically consist of three modules:

1.   pretreatment

2.   reverse osmosis membrane

3.   post-filter

RO Activated Carbon FilterPretreatment protects the membrane from fouling and damage caused by chlorine. It usually consists of a sediment filter and an activated carbon filter. The sediment filter removes particles such as dirt and rust, while the activated carbon filter removes chlorine and other chemicals.

The reverse osmosis membrane is the heart of the system. It’s a thin film composite (TFC) that remove contaminants from water. The TFC is made of several layers of material, including a semi-permeable membrane.

The post-filter is the final stage of filtration that removes any remaining impurities from the water. This is typically a second carbon filter that ensures the water is safe to drink and tastes great. It also includes a particle filter to remove any remaining turbidity.

Some RO systems include a water storage tank, which stores the clean water until you’re ready to use it. This is desirable because the flow rate through the filter is slow. Having a storage tank ensures you can fill a glass or a cooking pot quickly with clean water without having to wait.

How Well Does Reverse Osmosis Remove Odors

Reverse osmosis very effective at removing many compounds from drinking water, including odors. In fact, reverse osmosis is often used in commercial settings, such as restaurants and office buildings, to improve the taste and quality of the water.

1 – Removing chlorine odors with RO

A reverse osmosis system can remove all of the chlorine in tap water. The RO membranes, which normally is the primary method of treatment, does not reduce chlorine. In fact, chlorine can damage the membrane because it oxidizes the polymers it is made of.

So how does a reverse osmosis system remove chlorine? The carbon pre-filter – a component in all RO systems – removes the chlorine.

Chlorine is effectively removed by activated carbon. The US EPA considers carbon filtration a benchmark technology for removing chlorine from water.

The good news is – your reverse osmosis system will remove chlorine and those chemical odors from your drinking water. However, the activated carbon filter, not the reverse osmosis membrane, does the “work” of removing chlorine.

2 – Removing hydrogen sulfide odors with RO

Your reverse osmosis can most of the hydrogen sulfide in your drinking water. In some cases, the RO system may only remove part of this odor causing contaminant.

Removing hydrogen sulfide with RO works the same way chlorine removal does. The carbon pre-filter removes the H2S from the water. The membrane removes very little hydrogen sulfide, though.

The amount of hydrogen sulfide eliminated by the carbon filter is based on the type and quantity of carbon in the filter element. The carbon filters on an RO system typically remove 15 to 65% of the hydrogen sulfide present in tap water. If the hydrogen sulfide concentration is low, then the reverse osmosis unit can remove all of it.

Reverse osmosis is very effective at treating sulfate and sulfite in drinking water. Reverse osmosis can remove 99 to 99.99% of sulfate in water. Reverse osmosis can remove 99 to 99.9% of sulfite in water.

Factors to Consider with Reverse Osmosis

If you’re concerned about the quality of your drinking water, a reverse osmosis filter may be a good option for you. RO filters are able to remove a variety of contaminants from your water, including lead, mercury, and chlorine. However, there are a few factors you should consider.

Installation cost of reverse osmosis

Depending on your home’s plumbing, installing an RO system can be relatively simple or quite complex. If your home has a standard under-sink configuration, you can likely install the filter yourself. However, if your home has multiple faucets or you need to drill new holes for the filter, it’s best to hire a professional.

A whole-house RO system can be expensive to install, especially if you have to modify your home’s plumbing. An under-sink unit, on the other hand, can often be installed by a good do-it-yourselfer for a reasonable cost. Each home is unique, so you’ll have to determine which system is right for you.

Maintenance cost

RO filters have sediment filters and activated carbon filters that have to be replaced. A sediment filter will usually last for about six months before it needs to be replaced. Carbon filters have to be replaced every 3 to 6 months, depending on how much water you use and the amount of chlorine in your water.

The cost of replacement filters can vary, but you can expect to spend around $60 to as much as $200 per year on them. Whole house filters are 3 to 4 times as much as under-sink filters.

While this may seem like a lot, it’s important to remember that RO filters can remove a variety of contaminants from your water, making it safer and healthier to drink.

Whole-house versus under-sink unitsWhole House RO System Diagram

Another thing to consider is how much water you’ll need to filter. RO filters are typically sized according to the number of gallons they can process per day. If you have a large family or use a lot of water for cooking and bathing, you may need a larger filter.

Reverse osmosis systems are available in a wide range of sizes, from small countertop units to large industrial systems. They can be used for point-of-use (POU) applications, such as filtering water for a kitchen sink, or point-of-entry (POE) applications, such as filtering all the water coming into your home.

Deciding which type of RO system is right for you depends on a number of factors, including your budget, the size of your home, and your water quality. Read my article on under-sink RO systems and whole-house RO systems for a detailed explanation.

NSF certification

Reverse osmosis filter manufacturers often make claims about how well their units remove contaminants. The best way to be certain of their claims is to look for units that have been certified by NSF International.

NSF is an independent organization that tests and certifies products to ensure they meet strict standards for quality and safety. If a product has been certified by NSF, you can be confident it will perform as advertised.

The applicable standard for point-of-use reverse osmosis systems is NSF/ANSI 58. It covers the following parameters:

  • Materials of construction and leaching of harmful substances
  • Mechanical integrity
  • Removal of total dissolved solids (TDS)
  • Efficiency rating
  • Recovery rating
  • Contaminant concentration reduction


So, does reverse osmosis remove odor from drinking water? The answer is yes, but the removal efficiency depends on what the odor is and its cause.

RO can remove a chemical smell caused by chlorine or a rotten egg odor from hydrogen sulfide. In both cases, it is the carbon pre-filter that removes the source of odor in water and not the reverse osmosis membrane.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children. You can also follow him on LinkedIn, Twitter and Facebook.

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