Reverse Osmosis Water Tastes Like Plastic? Here’s What to Do

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Reverse osmosis water has been stripped of most things that give water any taste at all, so it shouldn’t ever taste ‘bad’. If it does, it is usually an indicator that your RO system needs maintenance or isn’t working the way it should.

One of the more common questions we get is, ‘why does my RO water taste like plastic?’

In this article, we will explore the reasons why your reverse osmosis water may have a plastic taste (or other tastes), and the appropriate steps to take if it happens to you.

Key Takeaways

There are various reasons your RO water could have a plastic taste, from how you store it to not flushing it when you should. It is essential to identify the issue so you can use the appropriate solution:

  • Improper storing – use food-grade container.
  • New RO system – flush.
  • Bad storage tank – replace.
  • Old/malfunctioning post-filter – replace.
  • Stagnant water – flush tank.
  • Problems with the source water/plumbing system – conduct thorough analysis.

Reasons Why Reverse Osmosis Water Tastes Like Plastic

There are a few questions to ask first.

  1. Number one, have you been storing your water in the fridge in a plastic bottle or storage container? If so, it’s time to switch to a food-grade container, as the plastic taste may be coming from the storage container plastic leaching into your water (RO water tends to be slightly acidic and thus more aggressive). Besides, plastic water bottles need to be replaced every three months, or they start to smell and affect your water taste. Stainless steel bottles are a much better option.
  2. The second thing to ask yourself is, how new is your RO system? If you have just installed it and are using it for the first time, the plastic taste may be due to fibers and manufacturing debris being flushed out. It is important to run 2 or 3 tank fills and dump that water first before getting to the properly flushed drinking water.

Bad Water Storage Tank

If neither of those things work, it may be the storage tank in your RO system itself that is giving the plastic taste. If your RO system uses a storage tank with a butyl bladder, the filtered water sitting there may be picking up taste and odor as it waits for you to use it.

Once minerals have been removed, RO filtered water can leach materials much easier than regular tap water, especially if it has been sitting in the storage tank for some time.

Under Sink Reverse Osmosis System

To counter this, if you haven’t had your tap on for a while, flush out the storage tank and see if the plastic taste is eliminated.

Most people also opt for a post filter, which helps to remove any residual taste after the water has left the storage tank.

If none of this works, you may have something wrong with the storage bladder inside the tank, and replacing the tank might be necessary.

Old Post-Filter

If you have a system with a post-filter, and your water begins to taste strange, it might be a sign that you need to replace said filter. An old post-filter that is no longer working will not be removing any plastic tastes the water might be picking up on its way through the reverse osmosis system.

Recent Post-Filter Replacement

If you have recently replaced the post-filter, it is possible that you may have purchased one that is not working. Replace it one more time or use a different model to see if that makes a difference.

Stagnant Water

If you have not run your faucet for a while, there is more chance of it picking up odors and smells from the storage tank. So if your water has been stagnant for a long time, drain the tank and let it refill before you use it.

Your Home’s Plumbing System

Most homes these days are fitted with plastic pipes for plumbing rather than older copper pipes. While plastic pipes are easier and cheaper to use, it is possible that they can cause water to have a residual plastic taste.

If you can identify your water as having a fruity plastic taste, or a rubbery taste, it is probably due to the PVC pipes in your plumbing system. Suppose your pipes are new; it’s essential to wait 14 days before use and to be thoroughly flushed.

Source Water

Your source water could be contributing to this too. As mentioned before, reverse osmosis purified water tends to be slightly acidic. And acidic water is known to leach more impurities out of plastic found in pipes, bladder tanks, etc. than alkaline water.

Is It Safe to Drink RO Water That Tastes Like Plastic?

If the RO system is working correctly, theoretically, the water is still clean and safe to consume. However, no long-term data is available on the potential health effects of exposure to plastic in drinking water.

If your RO water tastes strange because your RO system needs maintenance or is malfunctioning, your water may not be safe to consume as it likely has not been filtered properly.

What to Do About the Plastic Taste

  • Check and replace the post-filter.
  • Flush the system properly.
  • Store your water in food-grade containers or stainless steel bottles.
  • Follow the correct maintenance and filter replacement schedule.
  • Replace your RO system storage tank if all else fails.

Test the Quality of Your Water

There are a few tests you can do to figure out why your water might have a strange taste. The first one is a pH test to see if your water is too acidic. During reverse osmosis, alkaline minerals are removed from the water, which means the water is more acidic than regular tap water (but not even close to the acidity of a tomato, so don’t worry!)

This means that it is more likely to leach a plastic taste from the bladder of your storage tank. If the water is a little too on the acidic side, you could consider a remineralization filter to put the alkaline minerals back into the RO water.

You can also find tests to measure the possibility of plastic leachates in your water by using a plastic leachates water test.

Other Reasons Why Reverse Osmosis Water Can Taste Funny

RO water generally should not have much of a taste. Definitely less taste than tap water. So if the taste remains after filtration, then the RO filter system is not doing its job correctly and needs to be fixed. The type of taste your water has can give you an indication of what may be going wrong.

Metallic/Bitter Taste

This may be due to the RO water leaching metals out of your plumbing system. Another reason: There are various metals in the water that are no longer being removed, so your RO membrane needs replacement.

Chlorine Taste

While some people taste chlorine as bitter, others taste it very specifically as chlorine. A carbon pre-filter that removes chlorine before the water moves through the RO membrane is needed. If you already have one, replace it.

young woman drinking water

Salty Taste

This is often due to excess sodium/magnesium salts in the source water.


A sour taste is usually indicative of acetic acid. This is produced by bacterial growth in the RO system and means it will need to be thoroughly cleaned.

Sulfur (Rotten Egg) Taste

This comes from hydrogen sulfide that is dissolved in the water and is more common in areas where the soil contains excess sulfur.

This is not necessarily an issue with the RO system. RO membranes are not very good at rejecting dissolved gasses. You may need additional filtration.

Just Weird

Ensure that everything is installed correctly, your filters are being changed regularly, and that maintenance is performed on the system when needed to get the best-tasting supply. If you are new to RO filtration, the water itself will not taste like your regular tap water, but a little more flat and possibly slightly acidic.

Like Regular Tap Water

This suggests that the various filter elements of your reverse osmosis system have exceeded their capacity. Replace them!

Usually, the RO membrane can last a few years but will need to be replaced more frequently if your water is heavily contaminated or if your filters have not been replaced regularly. Speaking of, the pre-filters in a reverse osmosis system usually last between 6 and 12 months. The post-filter should be good for 1-2 years.

Chemical (Cleaning Agent)

This could be a plumbing issue. If you have a misplaced drain saddle or your plumbing fixtures have been improperly installed, then your RO water could be getting into contact with chemicals from your dishwasher and other appliances.

What Should Reverse Osmosis Water Taste Like?

RO water is usually described as having less to almost no taste as compared to unfiltered water. It can be pretty flat tasting due to the low levels of minerals in it. If the taste is a concern, you can remineralize the water after purification.

If you have any questions about why RO water tastes like plastic 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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