Why Does Reverse Osmosis Water Taste Funny or Bad? (+ Easy Fixes)

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The lack of any taste or smell in reverse osmosis water is one of the main advantages to this type of filtration.

Which is why noticing any kind of bad or funny taste in your reverse osmosis water should prompt you to investigate further.

It’s possible that it’s only a small, temporary issue, but it could also point to more serious problems that need immediate addressing…

Key Takeaways

Bad or funny taste in reverse osmosis water should generally be a cause for concern. Your reverse osmosis water may taste bad or funny for the following reasons:

  • A metallic taste is usually caused by corroding pipes – remineralize your RO water before distribution or replace pipes. You might also need to replace your RO membrane, flush or replace your storage tank, or add additional water treatment.
  • Saltiness can usually be traced down to issues with the reverse osmosis membrane – replace.
  • Sulfur taste points to hydrogen sulfide which RO doesn’t really remove – add additional treatment.
  • Sour-tasting RO water can be caused by a number of factors – replace filter elements and sanitize your entire RO system.
  • Plastic taste – replace filter elements and prime new ones properly; check the storage tank.
  • Chlorine/bleach taste – add/renew carbon filtration.
  • Unfiltered tap water taste – Check age of filter elements and if they have been installed properly.

Why Does Reverse Osmosis Water Taste Funny or Bad?

“Why does my reverse osmosis water tastes funny?”

Your reverse osmosis water may taste funny for a couple of reasons. You should start by identifying what exactly is causing the unusual taste – and this, in turn, starts by figuring out what the taste is in the first place. A sweet taste will probably be caused by different factors than a sour one, for example, though there are also some overlaps.

Metallic (Bitter) Taste

A metallic or bitter taste in RO water can usually be traced down to problems with your plumbing. Remember, reverse osmosis water is slightly acidic and hungry for impurities, so it will cause corrosion in your plumbing if it’s made out of certain materials like copper.

In this case, there are 2 things you can do:

  1. Remineralize your reverse osmosis water before it gets in contact with any metal/copper plumbing.
  2. Reroute your filtered water through another set of pipes.

By the way, this problem usually only exists with whole house reverse osmosis systems that distribute their water through the entire household, or if you’ve connected your point-of-use RO system to your refrigerator or ice maker which often use copper tubing.

Other reasons for RO water tasting bitter are:

  • An old reverse osmosis membrane that is no longer effective and needs replacement.
  • A leaching RO storage tank which you should flush or replace. You can also remineralize your RO water before storing.
  • Very high salt or metal levels in the feed water. Replace filter elements or add additional treatment.

young woman drinking water

Salty RO Water

A salty taste in reverse osmosis water often points to an issue with the reverse osmosis membrane itself. If the membrane gets clogged or needs to be replaced, it can start letting more solids through, resulting in a salty taste.

In this case, simply replace your membrane with a new one.

If it’s the case that your feed water is exceptionally high in salts, you should also consider adding additional filtration methods.

Sulfur Taste (Rotten Eggs)

A taste resembling rotten eggs is often caused by excessive hydrogen sulfide present in the feed water.

The problem is, RO is not very effective against gasses and hydrogen sulfide is such a gas.

Your RO system’s carbon pre and post-filters might remove some of the rotten-egg taste, but it’s likely that you’ll need additional pre or post-treatment.


Identifying the cause for a sour taste can be a bit trickier; a number of factors can come into play.

For one, a sour taste could point to bacteria growing in your RO system which means filter elements have to be replaced after full system sanitization.

Like Plastic

Plastic taste in your RO water can be caused by a malfunctioning carbon post-filter.

It’s also possible that you have a new filter which hasn’t been properly activated yet. With some filters, it can take a few cycles before they start to operate properly, and until then, you might notice some unusual plastic taste.

In addition, plastic taste can also develop when your filtered water is running through extensive sections of the wrong type of plastic tubing. An RO storage tank can also add a plastic taste to the water, especially stagnant water. The lower pH level of reverse osmosis water makes it slightly acidic, which can result in leaching different elements as it passes through plastic components.

What you could do is:

  • Check and replace your carbon post-filter if need be.
  • Flush your RO system properly.
  • Replace your RO system’s storage tank if the other measures don’t help.


High levels of chlorine in your feedwater can manifest in the filtered water as well, if you’re not using proper pre and post-filtration.

If you don’t have a carbon filter in place, now’s the time to get one, as it will most likely eliminate any tastes or smells resembling chlorine or bleach in your water.

RO Water Tastes Just Like My Unfiltered Water

If that’s the case, then the most likely reason is that water is not getting filtered at all. This is another reason to check your reverse osmosis membrane and all your other filters. In addition, check the system for leaks and ensure all valves are working correctly, and that the system has adequate pressure.

Factors Affecting the Taste of RO Water

Reverse osmosis water, by itself, has no smell or taste. That’s one of the main points in favor of investing in a reverse osmosis system in the first place. However, this can be affected by various factors. Some of those are not immediately obvious and require digging a bit deeper.

Low pH Water with Copper Piping

Since reverse osmosis water is completely pure, it has a slightly lower pH level than regular water, bringing it into acidic territory. This is normally not a problem as the acidity is nowhere near strong enough to cause issues with your health.

However, it can become an issue when combined with copper piping. Reverse osmosis water can start corroding the pipes, getting contaminated in the process.

High TDS Levels Remaining

Reverse osmosis reduces the TDS (Total Dissolved Solids) levels of feedwater very effectively – as much as 99% in some cases. However, it’s still not 100% perfect, and some percentage of the original dissolved solids will always remain.

If the TDS levels of your feedwater are sufficiently high, this can cause filtered water to have a noticeable taste or smell too.

tds meter in glass of water

Sulfur/Hydrogen Sulfide

Sulfur or rather hydrogen sulfide affects the taste and smell of water. Unfortunately, this is also one of the weak spots of reverse osmosis filtration. Even though it does remove small amounts of sulfur salts, it’s not really effective against hydrogen sulfide gas.

Problematic Feed Water

As we mentioned earlier, the contamination levels of reverse osmosis water are directly proportional to those of the feedwater. If there are severe problems with your input water, those will carry over to the filtered water to some extent.

Old RO Membrane

Remember to regularly replace your reverse osmosis membrane! If you leave it in place for too long, it will eventually stop working correctly and some contaminants will start making their way through.

Your reverse osmosis membrane should be replaced once every 2 to 5 years in most cases. This can be affected by the quality of your water and your consumption habits though, so your case might require more frequent replacements.

Old Pre/Post-Filters

The same goes for your pre and post-filters. All of those have to be replaced on a regular basis to ensure they’re working correctly. It can get a little hectic when you have a comprehensive reverse osmosis system with multiple pre and post-filter stages, each requiring its own replacement schedule. In this case, you should probably look into setting up a calendar or something else to help you keep track of everything.

How to Fix and Improve Bad RO Water Taste

Hopefully, by this point, you’ve managed to figure out what’s causing the bad taste of your reverse osmosis water. With that information available, you can proceed to the next step: Fixing the problem.


Adding a remineralization filter to a reverse osmosis system is recommended in general, as it helps mitigate the one main downside to that type of filtration – the fact that it completely removes all minerals from water.

By remineralizing, you can make flat RO water taste more rounded. It also increases the pH level of the filtered water, preventing it from corroding copper pipes and leaching from plastic ones.

Replace Filters

Make sure to replace all filters in your system regularly – both the reverse osmosis membrane itself, as well as any pre and post-filters you might be using. Keep in mind that the ideal replacement frequency for different filters varies across the board, so you might have to maintain a list of replacement dates to stay on the safe side.

Flush New Filter Elements

Sometimes, new filters need to be flushed or activated before they can be used. This depends on the exact model of the filter, and you should consult its manual for additional information. As a general rule of thumb, always give a new filter a few cycles to properly settle in before deciding that something is wrong with it.

Sanitize Your Reverse Osmosis System

You might also have to sanitize your complete system every once in a while. This is usually necessary when dealing with high levels of contamination, as well as certain specific contaminants like biological ones. Sanitizing a reverse osmosis system takes some time, so you have to plan ahead for it to minimize any disruptions to the water supply of your household.

Add Additional Treatment

It’s also possible that your current filtration setup is simply not adequate for what you’re dealing with. You might have to add extra filters to treat specific contaminants. For example, sulfur often requires a dedicated filter.

The only way to be sure that you’re addressing the full spectrum of contaminants in your water supply is to have it tested in a laboratory, so that you’ll know exactly what kinds of filters you need.

water filter cartridges and membranes

Avoid Stagnant Water

Try to avoid stagnant water, both before and after the filtration.

For example, if you’re sourcing your water from a large still reservoir, this can promote the development of certain unusual and unpleasant tastes, not all of which might get effectively filtered out by your reverse osmosis system.

On the other hand, if your reverse osmosis storage tank is too large, it could lead to situations where water has been sitting in it for hours, even days before you get to drink it. This can also cause a stale taste.

What Does RO Water Actually Taste Like?

Reverse osmosis water is almost completely pure water with no impurities – so it should have no taste or smell to it. That’s why noticing any taste in reverse osmosis water is usually something that should be investigated further. It very likely indicates a problem, either with your reverse osmosis system itself, or in another area of your plumbing.

If you have any thoughts about the question, why does my RO water taste bad, please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
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