How Much Water Does Reverse Osmosis Waste?

If you love drinking bottled water, then you may have come across the popular term reverse osmosis. It’s a process that involves the use of special filters to remove contaminants from water. The filter works by pushing water through a semipermeable membrane, which produces clean water, which is safe for drinking. 

However, the critical question is, how much water does reverse osmosis waste? Even though reverse osmosis makes up for an excellent way to filter water, it is a process associated with many concerns. Various factors come into play when using such systems which you have to consider. You have to get the correct RO system, and keep track of its usage to keep waste at the lowest level possible.

Thus, this guide aims to identify the critical aspects related to reverse osmosis and whether it leads to the wastage of water. Let us get started:

While you may come across several products that claim that reverse osmosis does not waste water, this is quite contrary to what happens. In fact, some brands go as far as claiming the “zero” waste occurs during the filtration process. However, the apparent reality is clear, and that is reverse osmosis leads to a significant amount of water wastage. 

Even if a filter uses an electric pump to redirect water, it’s still prone to water wastage during reverse osmosis. Even more, these pumps recycle water back to the filter, and this might lead to the increased wearing down of the filter.

Various factors come into play when it comes to determining the specific amount of water that is wasted from your RO pump. You may have to conduct additional research, or perhaps consult with the particular brand of your pump for further information.

Being able to track the amount of water that will be wasted is crucial when investing in an RO pump. A good pump is highly efficient, and it does well to reduce the waste levels to the lowest level possible. However, you also have to remember that any compromise in the functionality of the pump is likely to lead to increased water wastage. 

Thus, it would be good if you can also keep track of how you use the water pump and the recommendations of the brand maker. Maintaining the efficiency levels of your pump is not only about owning the right pump, but also keeping track of its usage.

How Much WasteWater is Produced?

In simple terms, an average of 4 gallons is wasted for every 1 gallon that is purified, if you are using a local water supply with adequate pressure. That said, it averages at 1 gallon of waste for 1 gallon purified when you use a permeate pump.

The amount of waste and clean water produced by such a system is dependent on various factors. Thus, before you can determine what comes out of the system, you have to learn how it works. All systems operate under specific metric levels, which are at 77°F, 70psi and 250ppm NaCl input challenge load.

There are a few key factors to consider when using a pump. For instance, any level below 40psi means that the pump will not be effective, and will only lead to the production of wastewater. Thus, if you have a well at home, check the pump and evaluate the length of the pipe from the well to the pump. Consider the setup of this pump in relation to analyzing the performance expectations of your chosen pump. Also, this information is useful when you want to get an electric booster pump. 

The temperature of the water also has the same side effect of performance, as the water pressure. You will expect more waste and a reduced productivity level in winter seasons, as when compared to summer.

Also, the challenge load is the amount and the type of salts that exist in water. The RO membrane has a rating of 20ppm NaCl (sodium salt). 

Measuring the water composition can be achieved through the use of a TDS meter. However, TDS is not a clear indicator of the water quality and only the water composition levels. This is because the TDS consists of salts, metals, and minerals.

How Often is the WasteWater Produced?

how much wastewater is produced?

In simple terms, as you open the RO faucet to produce a drink, the system will turn on and function for 60 minutes, for every gallon it produces.

Also, the RO systems consist of an automatic shut off valve. The valve operates as a standalone unit, or it can be installed into a permeate pump. Also, the pump will produce wastewater whenever it works to provide clean water. It will also operate until the tank is full, and you close down the RO faucet. Remember that while a RO system will dispense water in your cup fast, the RO system will draw out to refill the tank at a slow pace. On average, this amount averages at just over 45 gallons per day, which converts to 2 gallons produced every hour.

The amount will increase significantly when a few key factors are present. These include when the pressure is low, the water is cold, and the TDS (Total Dissolved Salts) level is high. Furthermore, remember that as your pre-filters wear out, they also get plugged up, and this may reduce the pressure directed to the membrane. This will, in turn, increase the wastage of water, while simultaneously increasing the production of water.

A system the functions correctly, will not operate at all times. However, it will work for a few hours if you produce a gallon of water, and the pre filters plug up in use. For this reason, you have to get “down and dirt” if you have any one of these pumps in your water supply system. This is especially true if you experience high levels of traffic in your property, or if you have many users of the filtration system. Using the filtration system excessively will also reduce the lifespan of the pump.

Why Do Reverse Osmosis Water Systems Waste Water?

These systems involve the use of a semipermeable membrane to remove impurities from water. The osmosis process functions when ions travel for low areas of concentration, to high levels of concentration. However, reverse osmosis does just as the term suggests, whereby the water moves in the opposite.

For reverse osmosis to occur, the systems must have a water source with pressurized water. This will help overcome issues such as osmotic pressure and will let water travel for high salt to low salt concentration.

The conventional water filter system involves the trapping of impurities in media such as activated charcoal. The reverse osmosis systems also work by direct water “across” and “through” the membrane. This helps to maintain the hygiene levels of the membrane.

Since water has to flow continuously through the cleaning system to purify water, this means that water must be wasted. Water is wasted to help clean the membrane and to help remove the concentrated salt levels.

While the actual ratio often changes based on different companies and system types, the most popular RO systems have 4:1 Waste Water to RO Water Ratio.

The Reverse Osmosis Efficiency Calculation

Calculating the efficiency of reverse osmosis systems is crucial. Most RO brands have varying efficiency levels, but you can still use information from a broad perspective to learn how it works. 

An efficient filter for RO should be able to reduce the water wastage to low levels. You should note that there are no pumps that are completely effective at reducing wastage of water when the filter is in use. 

Reverse osmosis systems have a rating level that relates to their efficiency levels in performance. It refers to the amount of waste to product water, as mentioned above.

It’s evident that the more efficient types tend to be costly. Just as you would expect, a cheaper system is likely to be inefficient, and in the long run, expensive to use as well.

Even if this is the case, it’s not a hard and fast rule! Thus, you may have to evaluate the efficiency ratings on your chosen reverse osmosis pump.

How Different Types of Reverse Osmosis Systems Use Water

Even if most reverse osmosis systems have some functions and features, there are some key factors to consider. For instance, with pressurized and prefiltered water passing through a semipermeable membrane, each system typically involves a unique filtration process.

Most reverse osmosis systems use the inherent water pressure to direct water through a filter. However, some types feature a secondary pump, which produces pressure, and leads to water production.

Remember, there is a trade-off that occurs at such a point. What is it exactly? Well, its because the membrane burns out faster, and RO membranes tend to be costly. Thus, you won’t have to replace them regularly.

Also, the conventional RO system tends to experience increased wastage of water when it’s almost full. The bladder in the tank experiences increased pressure, which might increase the stress on the system. As a result, less water travels through the membrane, and this can be associated with various issues. 

Some systems use special valves, which leverages the pressure from the system. The valve helps to regulate the backpressure, thus making the RO system highly efficient.

Reducing Waste Water Production from Reverse Osmosis

If you have a traditional reverse osmosis system or you just want to plan for your resources ahead of time, you will find it easy to reduce the production of wastewater. There are techniques you implement to help reduce and control the production of wastewater. 

First, if you have a conventional pressurized bladder type system, you have to avoid using a small amount of water for each session. The best approach to complete this process is to fill up a gallon with some water, and then use it for drinking water. Thus, whenever you want to drink a glass of water, you should draw it out from the pitcher, rather than producing 8 ounces from your RO system.

As indicated earlier, that last amount of water to fill the tank is produced through inefficient procedures, as the pump has often worn out. By filling up a jug ahead of time, you won’t have to use small amounts of water from the system as the day progresses.

Another factor to consider is to go for a highly efficient system. Even if most reverse osmosis systems seem similar, they vary significantly in the amount of wastewater they produce.

Go for a system that at least 2:1 waste to product water ratio. Usually, most filters need to have a 4:1 ratio. That last addition can cause the filter to increase the rate to well over 15:1 depending on your chosen filter.

Reusing the Waste Water

reusing the waste water

Being able to reuse water is a crucial aspect of using RO systems. Any water that you deem as not suitable for human consumption should be reserved for other purposes. Even with most wasteful units, there are various things you can do to regulate the production of waste. Here are some few techniques you should consider:

Usually, a reverse osmosis system consists of a drain line that does not have pressurized water. Rather than directing the waste line to your sink drain, where it flows to the sewer of your septic system, you can opt to collect the water in a large tank.

While RO water does not have adequate minerals, it’s still safe to use for various applications. For instance, you can use it for watering landscapes and various other non-drinking applications.

Remember that while the taste of water is not always pleasant, it won’t make any difference to animals such as pets or livestock. Provided the water does not have any significant pollutants, the animals will be safe when consuming such water. Usually, it’s nothing more than just tap water, which has a low level of contaminants and nutrients. 

Even more, you can use the wastewater to clean toilets, such as those that are used publicly. Keep in mind that filling your toilets with RO wastewater may not be an easy job. However, if you reside in a place that has low water costs or if you have an outdoor toilet, then consider using the pump.


There are many ways through which you can purify the water you consume. Using reverse osmosis is among some of the best ways to clean your water. However, you also have to consider the factors that come into play when such water is wasted. You have to keep track of the performance of your filter, and the amount of water you need to filter through the system. Any compromise or over usage of the water system resources is likely to lead to adverse effects on the RO system. Thus, remember to consider the information above to help you make a more informed decision when using RO resources.

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