Top 6 Innovative Ways to Reuse the Waste Water from RO Water Purifiers
Most Indian homes use RO water purifiers, but very few know about the side effects of using one.
This isn’t surprising. RO water purifiers provide reliable water purification, but they often lead to unnecessary wastage of water.
Should you stop using RO water purifiers?
OR
Should you stop worrying about the wastage of water?
Out of all the water purifier technologies, RO water purification is the most reliable. And if your home/office has high TDS water then you have no choice but to use an RO water purifier.
What if we tell you something that lets you enjoy trustworthy RO purification without having to worry about the wastage of water?
You just need to know about some easy ways to reuse RO waste water, and then take action.
In this guide, we’ll go through six actionable ways to reuse RO waste/reject water to reduce water wastage.
But first, let’s go over the basics.
Why Re-Use RO Waste Water?
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.
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 wastewater or reject water. The percentage of wastewater varies according to the RO purifier being used.
However, RO waste water can be used in various ways to avoid the overall wastage of water in your home or office.
Before we check out how you can use this waste water, let’s look at some things to be kept in mind beforehand.
Things to Keep in Mind Before Using the RO Waste Water
It is best to determine the TDS level in the rejected water before deciding to reuse it for other purposes.
To be 100% sure, if possible, the waste water should also be tested for the presence of inorganic and chemical impurities like Sodium.
In addition to the TDS level, a few websites and several videos on YouTube also suggest checking the pH value of the RO reject water. However, there would hardly be any difference in the pH value of the input water and the RO reject water. So you need not worry about the pH value of the Reverse Osmosis waste water.
Click to read: Why You Must Not Use RO Water in Battery?
How to Store the RO Waste Water?
The easiest way would be to drop the reject pipe in a bucket. But if your daily drinking water requirement is 20 litres then on average your RO water purifier would generate around 60 litres of wastewater.
Assuming you are using a bucket of 15 litres, you would need to empty the bucket 4 times a day. And the biggest pain is keeping a check on the bucket, so it does not overflow.
This may not be practical for a lot of users.
If you are one of those then worry not because we have a better solution for people like you.
You can extend the RO waste pipe and drop it in a big tank placed outside your kitchen. This stored water can later be re-used in one of the several ways listed below.
You can use a small submersible pump (like the ones used in water coolers) to take water from this tank. All you have to do is drop the submersible pump in the tank and connect it to a power source.
You can then use a water pipe connected to the outlet of the pump to draw water from the tank without using any bucket or container. A bigger tank also means that you do not have to worry about water overflow, as would be the case if you were using a bucket in place of a big tank.
The bucket, container, or tank used for storing Reverse Osmosis waste water should have a wide opening so you can easily clean the deposits at regular intervals.
6 Easy Ways to Re-use RO Reject Water
1. Wash Your Car
A single car wash could consume anywhere between 14 litres (for a car wash using a bucket) to 75 litres (for a car wash using a hosepipe) of water. Keeping in mind the scarcity of drinking water, using so much potable water for a car wash seems unreasonable and no less than a crime.
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 wastewater 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 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 wastewater 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 Reverse Osmosis waste water is to wash your utensils. Simply store the wastewater in a 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.
We found this useful YouTube video that shows you how you can easily reuse the RO waste water in your kitchen for washing utensils.
4. Floor Mopping
Using the RO waste water for mopping the floor is easy and will 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 Reverse Osmosis 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 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 that collects the RO waste water and use the wastewater 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.
6. Cleaning and Flushing Your Toilets
Another big source of clean water wastage in modern homes is the 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 a 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 that produces very little or no wastewater? Check out KENT RO Water Purifiers. These purifiers use Save Water Technology which recovers up to 50% pure water and stores the rejected water in a separate tank.
Every year we read and listen to the 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 a sufficient water supply, think of it as a privilege.
Do your bit by saving every drop of water. These small measures can make a lot of difference because EVERY DROP COUNTS.
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Can we use the RO waste water for aquarium water?
Well, that totally depends on the TDS and pH level of the reject water. Different varieties of fishes require a different water environment. You should check the water requirement for the fishes if the RO reject water meets the criteria then you can use. However, we would suggest not to use the RO reject water for a fish aquarium and instead use it for other purposes like the ones mentioned in this post.
Can we use RO again on the Reject Water ?
Won’t the concentrate from the RO return to the membranes? Again, can we channel the concentrate to the overhead tanks and at what meters?
We are not too sure if we understand you correctly but we believe by concentrate you mean RO reject water. How can reject water return to the membrane?
Yes, you can send the RO reject water to the overhead tank. This is precisely what Kent’s ‘Zero Water Wastage’ technology does.
Doing so is safe because a small amount of reject water is mixed with a large quantity of freshwater. This keeps the TDS level of the input water in check. Barring TDS level, RO reject water is actually much better than the unfiltered water. This water has already passed 2-4 purification stages before being discarded as reject water.
Can I sent Ro wastage water again in bore pipe???
No, we don’t recommend sending the RO waste water in the borewell. This will deteriorate the quality of borewell water in the long run.
more informantion.thank you
I am thinking to run the RO Waste water through UV treatment and then use for Floor cleaning Toilet Flushing and in washing Machines.
Please comment on the suitability
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.
Education and nature conservative ideas.
I want to know whether RO reject water can be used in air coolers
Please check the previous comments on this post. The answer to this query is already provided.
Any guideline from the pollution control board to use RO waste water for plantation/gardening.
We are not aware of any such guideline from the pollution control board regarding the use of RO reject water for gardening.
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.