Why Does My Reverse Osmosis Water Taste Sweet?

Why Does My Reverse Osmosis Water Taste Sweet?

Ideally, water should be tasteless and odorless. So, it’s only natural to be alarmed when you find your Reverse Osmosis (RO) water is sweet in taste. This may likely make you question the cause of the unusually sweet taste as well as wonder whether it can be harmful in any way.

If your reverse osmosis water is tasting sweeter than normal, it is likely due to a high concentration of natural minerals or an imbalance of pH levels. RO filters remove all heavy metals, chemicals, minerals, and other contaminants found in domestic water, resulting in softer and slight sweet tasting H2O that is 100% safe to drink.   

The water we are used to drinking has dissolved solids and minerals in varying concentrations that impart a certain taste. The absence of these minerals and contaminants in RO water often results in a slightly sweeter taste. However, there are other factors that could exaggerate the sweetness levels. Let’s learn more!

Reverse Osmosis Water Tastes Bad After Changing Filter – Water Treatment (purewaterblog.com)

Should Reverse Osmosis Water Taste Sweet?

When water goes through a reverse osmosis system, the sediments are filtered out and 92 – 99% of all the heavy metals, chemicals, and minerals are eliminated from the water.

This means that RO water is the cleanest drinking water one can opt for and does not have any particular taste except for a soft sweetness to it. The majority of people that use RO treated water for drinking say that it has no taste at all.

The multi-stage filtration process ensures water has a neutral taste. This makes it easier to tell if the system is malfunctioning simply by the taste of the water.

Salty, metallic, bitter, sour, and extremely sweet-tasting water is a clear sign that something is wrong with the reverse osmosis system.

Factors Affecting the Taste of Water – Sweet, Sour, Bitter, & Salty

RO water tastes soft and sweet because it is clean. However, if it tastes too sweet, it might be due to the factors mentioned below. In such a case, your RO water may not be safe to drink.

pH level

Water can be acidic or alkaline if it is more or less than 7 on the pH scale. Water with a pH level of 7 is not only safe to drink but also maintains a neutral taste. On the contrary, if the water is acidic (less than 7) or alkaline (more than 7), it develops a sweet, sour, bitter, or salty taste.

Ensuring the filters are in good condition, and are replaced periodically, will help maintain ideal pH levels. Acid injections and neutralizers can also be used to balance the pH of the water if it is found to be more acidic or alkaline.

Mineral content

Most of the time, it is minerals such as calcium and magnesium that impart a sweet taste to the water. The remineralization filter is likely causing the RO water to taste sweet.

If that’s the case, there’s no need to worry, as the high amount of mineral content in the water is perfectly safe to drink. If you are still not fond of the sweet taste, pairing the RO system with a water softener will help reduce the sweetness in the water.

Source of water

The source supplying water to the mainline also has a strong impact on the taste of RO water. Water sourced from wells often has a naturally sweet taste, because of the high concentration of naturally occurring iron and calcium in the water. Iron alone gives a bitter taste to the water but combined with calcium, the water turns sweet.


It isn’t always the high concentration of minerals that makes RO water sweet. Often it is the plumbing that is adding that extra dash of sweetness to the water.

New or old plumbing can contribute to the sweetened flavor of RO water. One way to get rid of this taste is to run water from the taps for a few seconds in order to clear the lines before pouring yourself a glass. The other, more expensive, option is to replace the plumbing.

Ruptured membrane & expired filters

If you notice an abnormal amount of funky taste in your water, chances are the RO system is not working properly, and either the membrane has ruptured or the filters have expired.

In case of a damaged membrane, the water ends up sitting in the system for a long time becoming a cesspool for microbes to develop and grow.

How Often Should You Change RO Filters for Optimum Taste?

RO water will taste good all the time when everything in the system is running smoothly. If you notice a taste change, get your plumbing checked and replace the filters at their recommended times. Not only will it maintain the taste of the water but will also extend the life of the RO system.

Read my article about changing your reverse osmosis filters.

Let’s have a look at how often the filters should be changed:

Sediment Filter Carbon Pre-Filter Semi-Permeable Membrane Carbon Post-Filter
Replace every 6 to 12 months Replace every 6 to 12 months Replace once in 2-3 years Replace filter every 12 months

Note: The carbon post-filter is responsible for the taste of the water and must be changed every 12 months, whether there is a problem with the water taste or not.

Frequently Asked Questions

Q) Why does water taste different everywhere?

Mineral particles, chemicals, and heavy metals contribute to the taste of the water. For example, spring water from the mountains is rich in minerals and has an entirely different taste from water sourced from a well.

Q) Does RO water taste like bottled water?

RO water and bottled water taste quite similar because popular bottled water brands also use RO system plants to filter water.

Read my article about which bottled waters are treated using reverse osmosis.

Q) How can we make RO water taste better?

The lack of minerals in RO water makes it taste different than regular unfiltered tap water. To return its pre-filter taste, you can use a remineralization filter which adds essential minerals back into the water giving it more of a natural taste.

Final Thoughts

An extremely sweet taste in the RO water is a sign of system distress and your unit might require a filter or membrane replacement. If the issue persists it is best to consult with your unit’s manufacturer or a water treatment expert. Conducting a water test might also shed more light as to the source of the sweet taste.

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.

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