Wastewater from RO System – How to Recycle, Reduce and Reuse it?

Can’t we just boil the water we drink?

Most of us would have a NO as its answer. The condition of water resources in India is not hidden from anyone. Thus, using an effective RO system is one of the utmost needs of the present time.

Also, there aren’t any doubts about the efficiency of a RO system for water purification. However, its major drawback is one leading concern in almost every household. Yes, we are talking about the wastewater from RO systems. Surely, the RO filtration provides highly purified drinking water but often, they cause a lot of unnecessary wastage of water.

On average, the RO system’s use leads to 75% water wastage of the supplied input water. The numbers are shocking, isn’t it?

So, should we stop using a RO, or should we start worrying about the wasted water? Well, you can avoid all these worries and focus on a middle way of recycling, reducing, and reusing the wastewater from the RO system.

Yes, you read that right. It is possible to reduce, recycle and reuse the water wasted during the RO filtration. We have summarized this informative guide focusing on all the essential aspects of water wastage concerning water wastage.


What creates water wastage in the RO system?

First, we should all be aware of what creates the wastage of water in an RO filtration system.

The quality of water sources is a big concern. More and more people are worried about the enhanced pollutant levels in borewell and municipal water supply, which is a major cause of many dangerous health problems and issues.

As a result, people are now using the best water purifiers instead of using a direct water supply. The most common way to purify water, amongst the many, is RO water filters. The filters are known for their accuracy in purifying water for various use.

While most people just look at the brighter side of using a water purifier, many ignore the other side of the coin. Here are few things that you may not be aware of in an RO filter:

  1. The membrane technology used in a RO filter uses additional water for purification.
  2. The additional water passes through the membrane and cleans the filter. This additional water is later discharged from the filter, which leads to wastage of water.
  3. It has been observed that during the normal functioning of the RO filter, nearly 3-times water is wasted as compared to what is purified. Such numbers are enough to direct our attention to the need for recycling and reducing water wastage.


The need of reusing or recycling the wastewater from the RO system:

The high percentage of wastewater from the RO system and the water scarcity levels in India are the two main reasons that call for the utmost need to reduce the wastage of water during the use of water purifiers.

As already mentioned, a RO system rejects 3-times more water than the purified water. If this is to be put in figures, a RO system purifies just 25% of the input water. You can only imagine how much water is wasted on a daily basis from these filtration systems.

This wasted water from the purifiers can be utilized for plenty of other purposes other than drinking. Thus, while using the purifier’s wastewater, you actually can contribute to control India’s water scarcity.


What should you keep in mind when planning to reuse wastewater?

After realizing the current situation and statistics, surely most of you must be planning to reuse and recycle the wastewater. But, wait. You simply cannot just save the wastewater from the purifier and use it; few things should be kept in mind.

Care enough to know about them?

The first thing you should keep in mind when planning to reuse RO wastewater is to check its TDS level. If the wastewater has a very high TDS level, it won’t be safe to use it.

Besides this, the water should also be tested for chemical and inorganic impurities. For being the surest about the quality of the wastewater, you can also check its pH level. You can use the water if there is hardly any difference between the rejected water’s pH value and the filtered water.


The easiest way to store the wastewater:

What should be your next step after being sure about the quality of the wastewater? Without a doubt, it should be storing the wastewater appropriately.

There won’t be any use of the wastewater if it is not stored properly. The water’s inappropriate storing will sooner or later degrade its quality, making it absolutely unsafe for any use. Thus, along with all the necessary things, you should pay keen attention to properly storing the RO rejected water.

To store the water properly:

  1. Do get an estimated idea about the total liters of water rejected on a daily basis.
  2. Make sure to use a bucket or a container big enough to accommodate the desired amount of water. Using a big bucket will ensure that there isn’t any overflowing problem when storing water for future use.
  3. It is suggested to use a bucket with a wide opening. This can make it convenient for the users to easily take off water for use.
  4. Also, be very particular about timely cleaning and maintaining the bucket/container. This will prevent any dirt or harmful chemicals from accommodating in the tank, which can ruin the water quality.
  5. You can either manually put and withdraw water from the tank, or you can use a small submersible pump for convenience. You can carefully add a submersible pump to the stored water and then connect the same to a power source. Later, you can use a water pipe to withdraw the required amount of water from the tank as and when needed without any hassles or inconvenience.


The various ways of better utilizing the rejected water from RO filtration systems:

Let us talk about the main thing now – reusing the rejected RO water for various purposes.

There are a variety of ways in which wasted water can make the best use. Here is the list of some of the possible areas in which you can utilize the water rather than simply wasting it.

Mopping the floor:

Mopping the floor

The very first thing for which you can utilize the wastewater is mopping the floor. You can suitably use the water for scrubbing your floors. However, as the wastewater is high with TDS value, do mix some freshwater with it.

The direct use of wastewater on the floors may cause staining and can also cause an unpleasant smell. Moreover, there can be some unwanted sticky residue on the floor if the wastewater is used without diluting.


Washing your car:

Washing your car

Are you aware that you use nearly 14 liters of water while washing your car?

Instead of using freshwater, you can use the rejected water from your RO system and contribute to saving the precious pure water. You can simply store the rejected water in a tank and later use it to wash your car.

You can also mix some freshwater with the wastewater to balance the TDS and salt levels. This will avoid the risks of getting any kind of stains on your car. You can keep 10% pure water and 90% of wastewater for cleaning and washing your car.


Water your plants:

Water your plants

One of the best uses of wastewater is watering the green plants in your garden. The high concentration of minerals and salts in the wastewater can be beneficial for your plants. The nutrients can help your plants blossom and grow fullest.

It is advisable to do a trial test first to avoid any kind of side effects on your plants’ quality. Take considerable time to observe the reaction of each plant with the use of the wastewater.

Here are some of the tips that you can rely on to ensure the best use of rejected water for gardening:

  1. Measure the TDS level of the water. The general range of TDS for gardening is 2100 PPM. Anything more than this can affect the plant’s quality.
  2. You should be sure of the water’s sodium concentration as a high amount of sodium can cause long-term side effects.
  3. The high amount of sodium can also ruin the soil quality, which ultimately will affect the plant quality.


Flushing your toilets:

Flushing your toilets

Surely using the rejected water is a big no for bathing, but it can make a suitable option for flushing your toilets. You can also use the wastewater for cleaning your toilets.

On average, washing or flushing the toilets can take up to 6-7 liters of water. Above all, the used water is completely wasted as it goes directly into the drains. Thus, instead of using pure and fresh water for flushing, you can use the wastewater and preserve the freshwater for some other better use.

Besides this, you can also mix some freshwater with the RO’s rejected water and clean the toilet seats and washroom tiles. However, if you observe any stains on the floor or tiles, avoid using rejected water for cleaning.


Bathing your pets:

Bathing your pets

If you have pets at home, you can use the RO wastewater for cleaning and bathing them. You need water for regular cleaning of your pets. Thus, it is advisable to use the rejected water rather than the normal water.

There are some pet sensitive to high TDS water; therefore, you should patch test the water first. If there are no allergic reactions or any other severe symptoms on your pet, then you can confidently use the water for washing them.

However, if you observe some allergic reactions, you still can use the rejected water but mix it with fresh water to balance the TDS levels. After washing, be sure to towel dry your pets so that all the wastewater dries from their body.


Use it for your laundry:


Laundry is another essential daily household chore that requires a large amount of water. And without any need of saying, all the water used for laundry is wasted completely. Thus, to prevent this, you can make use of the RO rejected water.

The dissolved salts and minerals in the water can help remove strong stains from the clothes. However, you should avoid washing delicate clothes in the wastewater. If necessary, you can mix a 2:1 ratio of fresh water and wastewater.

You can use the wastewater for cleaning your carpets, rugs, doormats, curtains, or any other heavy clothing that is not too delicate. Moreover, you can also use the rejected wastewater for soaking some of your laundries to remove the tough stains and greasiness.


Soaking your dirty dishes:

dirty dishes

Last but not least, you can make use of the wastewater for soaking your dirty utensils. Doing this can help to remove the stubborn stains for the utensils, including the stuck food and crumbs from the plates. You can soak your utensils after every meal to easily clean them.

Once all the grease is removed from the plates, you can then use soap and regular water for washing your utensils. It is advisable to wash your utensils with fresh water, in the end, to prevent any harm to your precious china.

As you have already soaked your utensils in the wastewater to get rid of the grease and food crumbs, you would need a very minimal amount of fresh water to thoroughly clean your utensils.

Before you use the wastewater for any of the mentioned purposes, you should once check the water’s TDS levels. If the rejected water contains a very high TDS level, it is absolutely unsafe for any household chores.

The use of high TDS levels wastewater will ruin the quality and will also cause severe issues and complications. Therefore, it is advised not to take such risks.


What can be the possible risks of using RO wastewater?

After knowing the need to reuse the wastewater from RO and the proper way to store it, you must be wondering about the risks of using RO wastewater. There are certainly some risks related to the rejected RO water. Therefore, you should be prepared for the same before using the water for your needs.

  1. The high TDS level in the wastewater makes it completely unsafe for drinking purposes. No matter what, you should avoid using the rejected water for drinking. Also, you should avoid giving the water to the pets and other animals as well.
  2. Moreover, if the TDS level is too high, the water shouldn’t be used even for other daily chores as you won’t be getting any satisfactory results.
  3. The inorganic chemicals and impurities present in the water can have severe health problems. If the water is highly contaminated, you may even get skin allergies if using the water for bathing, etc.
  4. Bad odor and smell can be some other problems that can make using the wastewater risky and concerning.
  5. Moreover, the use of wastewater for regular household activities can also leave some stains and salt residues after use.

Knowing all the concerning risks and issues about using the RO rejected water, you shouldn’t miss checking the water quality before use. Test the water against all the possible contaminations – its pH level, TDS level, and other available contaminations, if you want to use the water for any other tasks than those mentioned above.


Related FAQs:

Can the wastewater be used for the bathing purposes?

Due to the high level of TDS in the RO wastewater, it is not recommended for bathing. The high TDS concentration in the water is a clear indication of water hardness, which has consequences when used for bathing.

The use of rejected water for bathing can cause you several issues, such as:

  • Skin irritation and allergies
  • Hairfall due to the high salt concentration
  • The wastewater won’t be able to form any lather when used with soap
  • The hard surfaces of your bathroom will get stained

Using the wastewater for bathing is more a choice for different users. Many research types have indicated that the use of wastewater helps in the absorption of salt and minerals in the body, which can be beneficial.

Thus, whether to use wastewater for bathing or not should be a choice depending upon your skin type and health.


Can the wastewater from one RO be used in another RO for water purification?

No, using one RO’s wastewater into another is not advisable. This is because of the fact that the wastewater already contains high concentrations of salts and TDS, making it unsafe for drinking.

Thus, it makes no sense to use high TDS water in another RO for purification as it will just enhance the TDS and salt levels with low-quality water purification. Also, adding wastewater of one RO into another will have a higher risk of degrading its proper functioning and damage the RO.


Do different RO waste different liters of water?

The wastage of water from different RO systems may vary, but the issue certainly exists in every RO system. Depending upon the brand and type of the RO filter, the amount of water wasted can go up and down.

However, it is observed that almost every RO system wastes 70-75% of the input water and delivers the remaining as purified water. Therefore, no matter which type of RO you are using, it is suggested that you should plan something or the other to prevent, reduce and reuse the water wasted during its use.



You will surely find a RO system in almost all the urban houses. Thus, it is a much-needed concern to properly utilize the liters of water wasted during the use.

Reducing, recycling, and reusing the wastewater from RO are the 3 best ways to limit the overall wastage of water from the RO filtration. With your contribution to saving water, you can save the lives of many people and benefit the environment.

We hope this information would have given you many ways of cutting back on the RO system’s water during water purification. Besides these ways, you can use the wastewater in many other ways depending upon the quality and your imagination.

Please do share any other creative and better ways that you use for utilizing the wastewater from RO. You can also connect with us in the comment section for any query or concerning thought.

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