How Much Water Does Reverse Osmosis Waste

How Much Water Does Reverse Osmosis Waste?

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If you are obsessed with bottled water, we are certain that you may have already heard of reverse osmosis water filter. These filters are capable of taking out all of the impurities and contaminants from the tap water by pushing it through a semi-permeable membrane which gives out clean and 100% safe drinking water. But there is one question that often arises—how much water does reverse osmosis waste?

Despite the idea that a reverse osmosis water filter is affordable and convenient to use, there are several people who are against it because it wastes tons of water. But is it really true? That’s what this article is all about.

We will give you every piece of information you need to know about reverse osmosis water filters and discuss if the use of these machines only leads to high water consumption or not.

How Much Water Does Reverse Osmosis Waste? Does It or Does It Not?

You may find several reverse osmosis water filters that claim that they do not waste much water in the process of filtering. Some even claim that there is zero waste during the process. But the fact of the matter remains that water that gets wasted during the reverse osmosis filter process.

The companies that claim zero waste get away with that because they use an electric pump. This electric pump basically circulates all the water back again into the filtration system.

As you may have guessed it, this will ultimately wear down the water filter at a faster rate than usual. The other way to get the zero waste tag is by using that wastewater by putting it in the hot water line, which usually ends up in the dishwasher.

As much as there is going to be water wasted, there is one way where it can be saved through a more efficient process. You will find that certain reverse osmosis water filters have a permeate pump which basically reduces the wastage of water.

How Much of the Wastewater is Actually Produced?

There are about four gallons of water that are wasted to purify about one gallon of water. So, that’s a ratio of 4:1. That is assuming that your water supply comes from the municipal water supply and has really good pressure. In the case of permeable pumps, the ratio of water gained to water wasted is 1:1.

That’s just the simple answer. However, let us tell you a little more about it in detail. So, the amount of wasted and clean water is combined.

Before judging how much water gets wasted coming out of the filter system, it is essential to understand what goes into the water filter system. The way these figures, that is the wastewater and production, are calculated is at 250ppm NaCl input challenge load, 77°F, and 70 psi.

The water filter system will not even work if the psi is below 40. It will only produce waste water and not drinkable water. This is especially crucial for those who draw water from their own private wells.

Be sure, to constantly check the pump, measure its length, and connect it to where the reverse osmosis water filter is located. If everything is not ideal, then it is recommended to fix an electric booster pump.

A lot of people are also not aware that the temperature of the water plays an important role in determining how much water they will get from the water filter system. In summers, you will get more water from the filter than during the winters.

The challenge load mentioned earlier refers to the amount of contaminants found in the water. The reverse osmosis membrane is always rated at 250 NaCl, which is sodium salt.

You can measure the water composition in a very simple way by using a total dissolved solids or TDS meter. However, this is only ideal for measuring the water composition and not the water quality.

How Often is this Wastewater Produced?

The simple answer to this question is, whenever you open the reverse osmosis faucet to pour yourself a glass of water, the filter system will get turned on and operates for an hour approximately for every gallon that comes out.

Let’s discuss that topic further so we can give you a detailed answer to your question. Reverse osmosis systems have a feature that can automatically shut the valve off. This can either be a single stand-alone component or a part of the permeate pump. The production of wastewater will continue till the tank is full or when the reverse osmosis faucet turns off.

One thing you must know is that the speed in which the water is filled in your mug is way faster than the water that refills into the storage tank.

As mentioned earlier, the pressure dips depending on how cold the climate gets. If the climate is cold, the level of TDS also gets higher. Additionally, the pre-filters also get plugged, and this will also reduce the pressure to the permeable membrane, which will increase production of wastewater and reduce production of drinkable water.

A well-functioning reverse osmosis filter system does not run all the time, but it will run for a few hours if you have drawn one gallon of water.


So, how much water does reverse osmosis waste? The answer is very subjective. There is no doubt that there will be water wastage when you use a reverse osmosis water filter.

However, having a permeable pump will reduce the ratio of the water wastage with the production of drinkable water by 1:1, rather than a non-permeable pump at 4:1 which is worse.

Now, knowing all the facts and concepts stated above, do you think it’s worth buying a reverse osmosis water filter? If you’re still contemplating whether to buy water filter or continue using bottled water every day, just keep in mind that the reverse osmosis water filter is the safer and more efficient option. It will not only give you fresh and clean drinking water, it will also help you save and protect the environment.

About the Author Jack Wilson

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