What Are the Disadvantages of Reverse Osmosis Water Treatment?
Written by: Gene Fitzgerald // Last Updated: Jun 23, 2023
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While the pros far outweigh the cons of reverse osmosis water purification, that is not to say there are no cons.
Any water treatment system will come with its own set of advantages, along with its own set of disadvantages.
In this article, we will get into the details of the disadvantages of reverse osmosis to help you decide whether or not investing in a reverse osmosis water treatment system is right for you.
Contents
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Key Takeaways
The disadvantages of reverse osmosis water treatment are:
- RO water can taste a bit flat.
- Reverse osmosis systems remove minerals from water that are beneficial for health.
- Reverse osmosis filtration will always produce some amount of wastewater.
- The system does need to be periodically maintained.
- The reverse osmosis filtration process can take time.
- The system might be slow if you haven’t changed your filters on schedule.
- A typical under-the-sink system needs at least 2×2 ft of space.
- You will need to install a specialized, separate faucet designed for your RO system.
- Reverse osmosis systems need a direct drain connection under your sink.
What Are the Disadvantages of Reverse Osmosis Water Treatment?
So, what are reverse osmosis disadvantages?
Well, aside from the little bit of effort it takes to get your reverse osmosis system set up and running, the following are the most significant concerns people have when using a reverse osmosis filter system.
RO Water Tends to Tastes a Bit Flat
RO water is not going to taste like regular municipal water. In fact, a lot of the ‘taste’ in municipal water comes from its impurities!
Lacking impurities, some say reverse osmosis water tastes a little bit flat. This can easily be rectified with a remineralization step.
Essential Minerals Are Removed
Reverse osmosis systems are the gold standard for the removal of most water contaminants. Still, unfortunately, they cannot differentiate between what is considered a ‘good’ impurity, such as minerals like magnesium, and what a ‘bad’ chemical. Bottom line, RO removes the good stuff, too. This leaves your water without some minerals that may benefit you.
When you research reverse osmosis water filtration, this mineral removal concern pops up often, with a lot of negativity. And it can be justified. Because although we get most of our nutrients from food, people have different diets and not always very balanced.
The WHO recommends remineralizing low-mineral water with magnesium and calcium in order to prevent any negative health effects. This can easily be done by adding a remineralization post-filter to your RO system to pop those nutrients back into your water after it has been processed.
Wastewater
Reverse osmosis membranes separate contaminants in the water from the water molecules, giving you pure H2O to drink. Unfortunately, this process doesn’t separate all of the water from the stuff in it. Some of the water remains behind with the contaminants and is disposed of down a wastewater drain.
How much water do you lose? Well, that depends on your system and setup. Some will be less wasteful than others, but they will all create wastewater, anywhere from one 0.2 gallon of wastewater per 1 gallon purified up to 4 gallons of wastewater for every 1 purified.
You can install a booster pump if your system produces a lot of wastewater, and this should improve the ratio by a lot, or make sure when you are purchasing your product that you check the wastewater specifications of that particular model. Alternatively, you can use your wastewater for scrubbing dishes and other forms of cleaning, provided it is not overly dirty.
Ongoing System Maintenance
Reverse osmosis systems do require periodic maintenance, and if you skimp on it, it will cause issues! Luckily this maintenance is relatively straightforward and can usually be done by yourself at home without needing a professional. It is vital to perform your maintenance on time so as not to risk the integrity of your water.
RO Water Purification Is a Slow Process
The reverse osmosis process can take time. Generally, this is not an issue as most models come with a storage tank, which houses pre-filtered water at the ready for immediate use. It is an issue, though, if you use all the water in your tank before it has a chance to refill, and then you will find yourself waiting a few hours for it to do so.
The system might also slow if you haven’t changed your pre-filters on schedule and if there is debris clogging the RO membrane, so it is essential to keep up to date with the maintenance tasks.
Kitchen Space
There are various types of reverse osmosis systems available. Whole house systems will need a considerable space, and the more common point-of-use systems will require either counter space or space under your sink.
A typical under sink system needs at least 2×2 feet of space under the sink to fit, including the storage tank. You will need more space if you want a bigger or extra storage tank. You also need space in your sink for installing the dedicated RO faucet. If you do not have the area under your sink, installing it in a cabinet nearby is possible.
You Will Likely Need a Separate Faucet
You do not connect your RO system to your pre-installed sink faucet but instead to its own specialized and dedicated faucet. This may require drilling an extra hole in your sink or using the pre-drilled hole for your sink soap dispenser or spray hose.
Yes, it is important to use a faucet designed for your RO system, as using your regular tap means you have to use RO water for everything you do in that sink, which seems a waste. Plus, RO water is sent through its faucet at a lower flow rate than regular tap water, which doesn’t work so well with your large, traditional faucet.
Direct Drain Connection
RO systems need to be hooked up to the drain pipe under your sink to dispose of all the wastewater we discussed earlier. The disadvantage is that you need to connect a wastewater saddle to your sink drain when you install it and ensure it is far away from your dishwasher disposal. This can be a little fiddly for some, especially if you have limited space.
Further Reading:
What Is an RO Water Filter System and How Does It Work?
A reverse osmosis system comes in three at-home varieties, whole house, under sink, and countertop, with under sink systems being the most common. Under sink and countertop systems are known as point-of-use systems, as they only filter the water coming to that area of use rather than filtering the water of your whole house.
They all work basically the same way when it comes to filtration. Your feed water is pushed through some pre-filtration steps that remove certain contaminants, and then pressure pushes the water through a reverse osmosis membrane. This semipermeable membrane traps contaminants on one side, not allowing them through to the clean water side and only allowing H2O molecules to pass.
Advantages
Lastly, let’s get to the advantages of using reverse osmosis:
- Broad contaminant removal: Listing every single contaminant that reverse osmosis filtration systems remove would take forever (it’s a lot!), but in terms of contaminant groups, it removes:
- Sediment
- Water disinfectants (e.g., chlorine, chloramine)
- Disinfection byproducts (e.g., TTHMs)
- Volatile organic compounds
- Nitrite/nitrates
- Pesticides
- Herbicides
- Heavy Metals (e.g., lead)
- Metalloids (e.g., arsenic)
- Transition metals (e.g., chromium 6)
- Salts & minerals
- PFAS
- Emerging chemicals/pharmaceuticals (e.g., BPA)
- Microorganisms (bacteria, viruses, cysts)
- TDS (total dissolved solids)
- Reverse osmosis is the gold standard of water filtration systems and provides water that is often cleaner than bottled water.
- Reverse osmosis water smells better and tastes better, making it easier to drink more of so you stay hydrated!
- The under sink units have a storage tank, which means filtered water is usually always available for you on demand.
- If you mainly drink bottled water, RO filtration will save you money in the long run, and also the use of plastics from bottled water purchases will be eliminated.
- They are easy to install and maintain, and you can usually do it yourself!
- Some systems can be customized to suit your needs, such as the ability to install extra filtration steps or run a line to your coffee machine.
- RO systems are energy efficient.
- They remove sodium from the water, which is helpful if you are using a water softener and need to reduce your salt intake.
If you have any questions about reverse osmosis disadvantages please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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