Top 6 Innovative Ways You Can Use the Waste Water from RO Water Purifiers

Using RO water purifiers not only gives us safe, clean and tasty water but also protects us from life-threatening waterborne diseases.

But there is one big drawback of using RO water purifiers i.e. the excessive wastage of water. An average RO purifier wastes approximately 3 litres of water for every 1 litre of purified water. That means only 25% of water is purified and 75% of water comes out as waste.

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Wondering why so much water is wasted? Reverse Osmosis (RO) purifiers use membrane technology to filter dissolved impurities, the impure water is filtered out and is often called waste water or reject water. The percentage of waste water varies according to the RO purifier being used.

Because of the high level of impurities and dissolved solids this reject water is not fit for drinking or bathing.

However, the RO waste water can be used in various ways to avoid overall wastage of water in your home or office.

Before we check out how we can use this waste water, it is important to keep some basic things in mind to avoid any issues or problems.

Things to Keep in Mind Before Using the RO Waste Water

It is best to determine the TDS level in the reject water before deciding to reuse for other purposes. Because if the TDS level is too high in the RO waste water then it might not be suitable for reuse in most of the applications given below. See how you can check the TDS level of water.

To be 100% sure, if possible, the waste water should also be tested for presence of inorganic and chemical impurities like Sodium.

The bucket, container or tank used for storing RO waste water should have a wide opening so you can easily clean the deposits at regular intervals.

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Learn more about some other limitations of RO water and how to overcome the same.
  1. Wash Your Car

    A single car wash could consume anywhere between 14 litres (for car wash using a bucket) to 75 litres (for car wash using a hose pipe) of water. Keeping in mind the scarcity of drinking water, using so much potable water for car wash seems unreasonable and no lesser than a crime.

    Car Wash
    We believe, washing cars every day not only wastes a lot of water but is unnecessary. If you are using an RO water purifier at your home or office then you can simply store the waste water in some tank or bucket and reuse it for washing your car. Water with a TDS level of 1200 – 1500 PPM can be safely used for car washing. If the TDS level of waste water is high you can mix tap water to dilute it. This should lower down the TDS level.

  2. Watering Your Plants or Home Garden

    If you are someone who loves gardening or have planted some plants in pots, the waste water can be used for watering your plants to keep your indoor or terrace garden green. This tip is particularly useful for people living in urban areas as the TDS level in municipal water tends to be lower.

    To be on the safer side, you can start with a few plants. Use the RO waste water for 15-20 days and check its effect on the growth of your plants. Each plant will respond to this change differently, which will give you a clear understanding of which plants are responding better to RO waste water. For gardening/irrigation use, a TDS level of up to 2100 PPM is permissible. You should also check out the percentage of Sodium, it should be less than 60 % ( 1.e. Na / Na + Ca + Mg). High Sodium content causes loss of soil porosity and therefore harmful to soil fertility in the long run.

  3. Wash Your Utensils

    Another useful application for RO waste water is to wash your utensils. Simply store the waste water in bucket or tank, make sure you place the bucket for collecting RO waste water near your kitchen sink so it can be used easily when you clean your utensils.

  4. Floor Mopping

    Using the RO waste water for mopping the floor is easy and will definitely save tens of litres of clean water every day. If you have a bigger house then the savings could be in hundreds of litres every single day. If the TDS level of waste water is high (over 2000 ppm):

    • Dilute waste RO water with an equal quantity of tap water. Because plain RO waste water with high TDS may stain or leave salt particles on the floor.
    • Use the RO waste water for floor mopping on alternate days. This will reduce the chances of any stains or salt deposits.
  5. Pre-rinsing Laundry

    You can use the RO waste water for daily laundry as well, but please keep in mind that using high TDS water might not be suitable for some delicate fabrics. Most of the Indian homes now use washing machines, though washing machines save a lot of time and effort but also result in a lot of wastage of water. You can create an overhead tank which collects the RO waste water and use the waste water from this tank directly in your washing machine (do keep in mind the fact about delicate fabrics)? This tip works best for semi-automatic & twin tub washing machines.

    RO Waste Water Used for Washing Clothes
    Image Source: Facebook

  6. Cleaning and Flushing Your Toilets

    Another big source of clean water wastage in modern homes is use of toilet flush. Every single flush sends approximately 5 to 7 litres of potable water down the drain.RO waste water can be used effectively to reduce this wastage of clean water by using it to flush your toilets. When you start, always monitor your toilet seats for any discoloration on porcelain surfaces after few days. With a periodical cleanup using common toilet cleaners, the chances of discoloration and salt deposits can be avoided.

Looking for an RO purifier which produces very little or no waste water? Check out KENT RO Water Purifiers. These purifiers use Save Water Technology which recovers 50% pure water and stores the rejected water in a separate tank.

Every year we read and listen to news of farmers committing suicide because of droughts. And there are thousands and lakhs of families in our country who have to travel for miles every day to collect drinking water. If you are fortunate enough to be blessed with sufficient water supply, think of it as a privilege.

Do your bit by saving every drop of water. These small measures can really make a lot of difference because EVERY DROP COUNTS.

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  1. A very well written article. Water Scarcity is one of the major issues in our country and should be handled properly. Thanks for such a wonderful post.

  2. The article is excellent on how we can reuse the RO disposed of water.

  3. Very useful information….it is the duty of every human being to save water for future generations.

  4. Is that right to send the impure waters into the well?pls answer …..

    • If that well is not being used for drinking water then you can dispose the water in the well. But we would highly recommend to re-use the RO waste water, if it is not possible to re-use then you can dispose the RO waste water in the drain.

  5. A well explained article helpful in understanding one’s requirement and good informations related to recycling of waste water.

  6. Depleting water table is a timely warning to use water judiciously. Have mercy on our progeny. Save them from dehydration. Save water Now.

  7. One more way of using the water wasted by RO is to fill the room cooler. It’s easy : put the RO pipe in a hose pipe insert the other side in the cooler hole.

    • An excellent article and an eye opener to all RO users.

      I’m just thinking aloud below.

      Many households these days use RO. Let’s take an apartment at least out of 20 houses 7-8 would be using RO.

      Is there a possibility that we can collect all the wasted RO water from individual household together in a large tank and use it for various purposes. There are lots of huge apartments. Apartment wise is it possible to do this.

      During installation of RO is it possible to take care of this. The water coming as waste being re-routed through a pipeline from those households using RO.

      We all have water tanks. Another big tank could be used to collect this wasted water from RO. This could be used for various other reasons stated.

    • Thanks for providing the valuable tip. Yes, it can be used in water cooler but you will have to keep a regular check on if water pump and water sprinkling holes (on top of pads) are not being choked. If the RO reject water has very high TDS then it can choke them.

  8. Can we use the waste Ro water for bathing ?

  9. Hii can we use waste water again in water purifiers and so on

    • It is not advised to re-use the waste water for re-purification because this will reduce the life of your filters, membrane and overall system.

  10. Can the reject water let in back to ground.

  11. Excellent & Educative

    • In city where people are getting rain water with municipal filtered and treated water still using RO. Any water which comes out as waste can be used any where.

  12. we get 36 liter waste water per 6 liter purified water. Product Eureka Forbes RO Elegant Is it O.K.

  13. As you are saying it’s use for moping and cleaning utensils I think it’s a play with your health the waste water in my opinion with have bacterias and viruses also and after regularly use of this you orally inhale it and it eat through utensils and can cause harm.It should also think that over head tank may contain eggs of mosquitos so please.think first and then use.

  14. I think the best idea is to return the reject water to the main water tank weather overhead or underground. in this case the least reject water will be mixed with the much water coming to the tank. so will reduce the effect of the salts and other harm matters

  15. won’t it harm plants if they are hydrated by the waste outlet water of my purifier?….. because that water contains dissolved oraganic and inorganic salts… maybe harmful to plants?

    • You’ll have to check the TDS level of the RO waste/reject water.

      We think that RO waste water with TDS levels of up to 2000 mg/l can be used for gardening.

      However, it all depends on what all the RO waste water contains. The best advice we can give you is you can try using it on 1 or 2 plants and notice the growth for some time. Discontinue the use if you notice any side effects like plants not growing as fast or drying of leaves.

      We have been using the RO waste water for watering our plants, without any negative effects on plant growth.

  16. Any guideline from the pollution control board to use RO waste water for plantation/gardening.

  17. Education and nature conservative ideas.
    I want to know whether RO reject water can be used in air coolers

  18. In one of the training session in Pune, by Plumbing Engineers Association, they warned that RO reject may contain harmful bacterias. It is not suitable to wash utensils. Advised not to reuse it unless fully tested. This testing is not readily available to an individual user. Hence safe way is to throw away the reject. What are your views?

    • Yes, if the source water is contaminated with microorganisms like bacteria then RO reject water may also contain such impurities. But, in that case, you are anyways washing your utensils with bacteria-contaminated water i.e. the raw water. Because we don’t think anyone washes their utensils with RO purified water.

      The above suggestions to re-use RO reject water may not be applicable for every home and depends on the quality of reject water. A suggestion like washing utensils with reject water might not be a valid option for most Indian homes. But it is definitely a good option for homes that suffer from acute water shortage and RO purification is the only choice.

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