6 Innovative Ways to Re-Use the RO Waste Water

Last Updated on 13 February, 2024 by Sourav Roy

Having a water purifier at home certainly makes life more comfortable. In fact, having one of the best water purifiers means you get to keep your water free of dangerous pollutants like heavy metals, viruses and bacteria. However, despite all that, not all the water that goes through the process comes out purified. Most water purifiers make use of the RO Purification technology to make the water clean. But, the process also creates RO Waste Water.

Re-Use RO Waste Water

RO Purification technology is the most efficient and recent means of getting safe drinking water. While this really does give you clean and pollutant-free water to drink, it also has the side effect of making wastewater that can’t be drunk. To clarify, for each litre of water these machines purify, they waste 2-3 litres, depending on the TDS level of the water source.

Though the water isn’t suitable for drinking, due to the high concentrations of organic and inorganic salts, you can still make good use of the water. In this article, we’ll tell you how to make the best use of RO Waste Water. That way, you can even save the effort of bringing in new water for other purposes.

Recommended Reading: Top 9 Best Water Purifier in India (2024): Expert’s Pick


Why RO water purifier creates wastewater?

So, let’s start with the basics first. Water purifiers are supposed to purify water, so why wastage? Well, RO water purification filters out impurities from water by using additional water.

The extra water cleans up the filter, after which it gets discharged by the purifier, taking all the harmful elements with it. This is what causes water wastage. To put it in perspective, some research studies show that RO water purifiers discharge three times the water they purify. That’s as much as 80% of the water you’d put inside the purifier.

Of course, you can still use the water, but only in certain ways, otherwise, you’ll have to deal with unnecessary problems.

Recommended Reading: RO (Reverse Osmosis) Water Purifiers – Pros and Cons


What are the dangers of using RO Waste Water?

As we’ve mentioned earlier, the discharge water rejected by the RO filter isn’t something you should be drinking. The water contains inorganic salts and organic matter in copious amounts. Besides, the water also has a high amount of TDS (Total Dissolved Solids).

If you were to drink that water, the first thing that you’d have to deal with is a foul stench and bad taste. Even more, the contents in the water have also been linked to severe health problems like stunted growth, reproduction failure and much more.

In some instances, you can’t even use the water for other things. Using wastewater for daily chores can leave you with stains and salt residues. There are still ways you can reuse this water, though.

Recommended Reading: Safe Drinking Water Guidelines in India


Why should you Re-Use RO Waste Water?

The best RO purifiers can still produce wastewater, even if they’re the best at making clean water. Water is an essential resource in every circumstance. For instance, if you live in an area where water is hard to come by, you’d have to save as much water as possible. Even in the relatively water-rich regions, you’re still hauling in large amounts of water into your purifier just to make sure you stay healthy.

You do get pure water in the end, but you’re still having half of your efforts wasted. After all, you get less than half of all the water you put in. You can still make this go in your favour if you make good use of the rejected water.

If you use that water, instead of letting it go to waste, then you make water worth your efforts as you don’t have to go to the source and fetch more. What makes this even better for you, and everyone else is that you save more of the water around you.


How do you collect RO Waste Water?

Storage is going to your first concern, once you decide to make use of the wastewater. Dropping the reject pipe into a bucket won’t work, as your water purifier can generate as much wastewater as three times the amount of your daily drinking water requirements. You’d need to set something up specifically for the situation.

You could use a bucket, but even with a large bucket like a 15 Litre one, you’d still need to empty it at least thrice a day. Besides, using this process means you have to put in the time to keep a check on the bucket, to make sure it doesn’t overflow.

That’s easily as much effort as not using the wastewater and going for alternatives. However, there is a better way.

You can put the RO waste pipe into a big tank outside your kitchen instead, by extending it. Afterwards, you can just leave it that way and let the water collect for you to make use of later.

You can also use a small submersible pump to draw water from the tank easily, without using any containers or buckets. You simply have to drop the pump into the tank and connect it with a power source.

Once you have the pump set, you can use a water pipe connected to the outlet of the pump to draw out the water. The best thing about using a tank is that you don’t have to check it constantly for water overflow. You can just leave it there, while all the water collects in the same place.

However, do make sure that the bucket, container or tank you use for storing the RO Waste Water has a wide opening. You’re going to need that, to clean out the deposits regularly with ease.

Recommended Reading: How to Save Water – Best Tips


Innovative Ways to Re-Use the RO Waste Water

Now that the collection is taken care of, let’s talk about what you can actually do with the water. While we did say that the water isn’t suitable for daily chores, that isn’t true for all cases. We’ve run some tests and compiled a list of ways you can use the water, without having to deal with the side effects.


1. Mopping The Floor

Mopping is one of the best uses of RO Waste Water. You spend quite a lot of water for doing that every day anyway, so using the water you store will reduce your efforts and save water. You can use the wastewater in case of both mopping and scrubbing the floor.

However, there are still some things you need to keep in mind. If you use only wastewater, you’ll have sticky or greasy residues over the surface sooner or later. You can easily prevent this problem by diluting the water. Just swap between using the reject water and fresh, clean water on different days.


2. Car Washing

Washing your car is one of the best ways to make good use of RO wastewater, as you save up a lot of home resources. It’s said that cleaning a car can take as much as 14 Litres of water, which is a large amount.

But, instead of wasting potentially pure water, you can just go ahead and use the filter discharge. After all, you’re going to have much more wastewater at hand than that. All you’d need is a reject tank or bucket, and then you’re all set.


3. Watering The Plants

While you can’t consume the water, your plants certainly can. Watering is the most convenient and effective use of RO Waste Water. So, you can put the water into the plants on your garden or balcony. They’ll grow without the water causing any problems.

In fact, the water’s content can actually work as nutrients for the plant, accelerating growth and keeping it healthy. This especially stands true in urban areas, as the TDS levels of the municipal water are much lower.

Use a bucket or watering can to store the water, and use it on the plants you have indoors or outdoors. We recommend going through a trial first to make sure there are no adverse effects, though. This is an essential step because each plant has a different reaction. Here some things you can keep in mind to make sure your plant benefits from the water.

  • Measure the TDS level of the rejected water. The highest TDS levels compatible with irrigation and farming are 2100 PPM.
  • Take note of the sodium percentage and ensure it won’t cause long term harm. Too much sodium can change the texture and structure of the soil, leading to lower yields with the plant.


4. Washing Utensils

Using RO Waste Water for cleaning your kitchen utensils is another excellent way. It’s going to be even more convenient for you if you install the RO filter in your kitchen.

You’ll be saving a lot of water because an average faucet puts out as much as 2 gallons of water a minute, which leads to much more waste. The reject water is the perfect alternative for you to get equal cleaning with lesser wastes.

For the best results, you can leave the utensils soaked after each use. The soaking will get rid of crumbs, and food stuck on surfaces while getting rid of the grease at the same time. Just make sure you do a freshwater soak at the end to avoid any salt deposition.


5. Toilet Cleaning

Toilet cleaning is another way you can get rid of the wastewater effectively. It makes more sense to use bad water with dirty toilet water, instead of putting in litres of good water. When you flush, you use up about 5 to 7 Litres of clean water that can be used on other tasks.

Just be on the lookout for any discolouration once you start using the RO Waste Water, as that can mean salt deposits are building up. Clean your toilet occasionally like you would when using the toilet without the wastewater, and there won’t be any deposits.

Additionally, you can also use the water to clean porcelain tiles and the toilet seat, after you dilute it with regular freshwater.


6. Pre-Rinsing Laundry

Using a good washing machine can give you a powerful and effective wash. However, a considerable amount of water gets wasted in the process as well. If you use RO Waste Water instead of fresh water, you will save a lot of the clean water that you can put to other uses. Another benefit is that the dissolved salts in the water can help remove stubborn stains.

Keep in mind, though, that the water with high levels of TDS might not be suitable for delicate fabrics.

You can also opt to put an overhead tank and make the RO Waste Water collect there and have the wastewater go directly to your washing machine. Semi-automatic washing machines and twin tub washing machines work the best with such arrangements.


Should RO Waste Water be used for bathing?

RO filters remove the hardness of the water so you can have clean, drinkable water. All the hardness is concentrated in the wastewater the filter discharges. So, you’ll be putting your boy in contact with a lot of unhealthy water.

We do not recommend bathing with the reject water, as that can be harmful to your health. For instance, the high TDS in the water can irritate your skin. Then you also have to deal with hair fall, as the water has increased salt content. Convenience is going to be an issue as well, as the hard water won’t let your soap make later.

Besides, when you’d be using it as bathwater, you would be spreading the wastewater all over the bathroom. Then you’d have to deal with stains all over your tiles, porcelain and showerhead.

In the end, it’s all upto you. Research shows mixed results. Some doctors even encourage the TDS water, citing that the skin can absorb the salts and minerals, benefitting the body. They say that the water can be just as good as bath salts.

Nonetheless, be sure to dilute the water at least, if you’ll use it for such purposes. Doing so will prevent hair fall and skin irritation.



The number of urban houses that use RO filters is increasing each day. It’s essential, especially with the high levels of contamination and pollution all around. RO purifiers do contribute to a lot of water wastage, but there are ways to cut back on that.

Keep three things in mind- always recycle, reuse and restrict. If you use your water efficiently, you can make life easier for yourself in the long run. Having the best RO purifiers helps as well. Brands are working on reducing the RO Waste Water discharged from the purifiers. In the meanwhile, we can make good use of the wastes in the ways mentioned earlier.

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