6 Tips for Effective RO Waste Water Reuse – No Water Wastage

Installing a Reverse Osmosis (RO) water purifier in a house is not a big deal at all. Most of the households nowadays are using water purifiers. You need these purifiers because the quality of the water source is not satisfactory. These RO water purifiers do a great job of purifying water, but they waste a lot of water in the bargain. Estimates show that these filters waste 3 litres of water while purifying 1  litre.

What is the effect of wastage of water from the RO purifiers?

Though you find water abundantly on earth,  only a small percentage of water is clean enough to use. Without a doubt in the future water is going to be a scarce resource and wasting 75% of water while purifying it and rendering it unfit for human consumption amounts to a criminal wastage. It causes a great strain on the sewage system because of the excess wastage of water. This wastewater contains a lot of organic and inorganic salts. Therefore, it is not fit for human consumption.

Is there any way to recycle this wastewater?

It is not advisable to recycle this wastewater back into the machine. But, there are ways to use this wastewater in a better manner. Let us look at these aspects and see how we can use this water effectively. However, prior to using it for other purposes, it would be better to check the TDS levels. In case the TDS levels are too high, it might not be reusable.

6 Tips to Use Wastewater From RO Water Purifier

1.  Watering plants

The reject water from RO water purifiers is useful for watering plants up to a certain extent. You can use this wastewater for watering your indoor and terrace gardens. This tip is very useful in cities because of the inherently lower levels of TDS in municipal water. You might not be able to use the same in rural areas or in areas where the TDS level of reject water exceeds 2100 ppm. Checking out the sodium levels is also necessary because excess of sodium can cause soil damage and affect the fertility of the soil.

2.  Washing your car

Washing your car should not be a problem with this wastewater. This should be one of the best uses of reject water from the RO water purifiers. In fact, you can see that you would need a minimum of 15 litres of water to wash a car (in case you use a bucket). This can even go up to 75 to 80 litres when you use a water hose directly from the main pipe. In this age of drinking water shortage, it is no less than a crime to waste good water for washing your vehicles. The wastewater from these water purifying machines provide the perfect alternative.

Water with TDS in the range of 1500 to 2000 should be fine for washing cars. In case the TDS levels are more than 2000, you have the option of diluting the wastewater with water from the tap. It is advisable to dilute the wastewater because the salt deposits can stick to the body of the car. Washing the car with a bucket of clean water immediately afterwards can be of great help.

3.  Mopping the floor

The advantage of using this reject water for mopping the floors is that you can use wastewater with TDS levels over 2000 ppm as well. You will be able to save large quantities of water in this manner. However, you should exercise the following precautions.

  • Use tap water to dilute the waste water from the RO purifier. You need to do this because the high TDS content in wastewater can cause salt stains on the floor.
  • Using wastewater for mopping the floors on alternate days is advisable. In this way, you safeguard your flooring from accumulation of salt deposits.

4.  Washing utensils

This is one of the easiest uses of reject water from the RO water purifier. Usually, you have the water purifier in the kitchen. You can collect the wastewater in a large utensil and store it for washing your utensils whenever you need to do so. Ensure that you wash the utensils again with tap water to remove traces of salt deposits that could stick to your utensils.

5.  Cleaning and flushing toilets

Your toilet flush systems waste a lot of clean water. Every time you flush your toilets, you waste a minimum of 5 to 7 litres of water. You can use this RO waste water instead. You have to make elaborate arrangements to connect the RO water reject pipes to the toilet flushes. This may be an expensive affair, but you save a lot of water in the bargain.

You can also use this water to clean the toilet floor as well. Check for discolouration of the toilet floor and seat every few days. In case you find any discolouration, use a regular toilet cleaner to eliminate the salt deposits.

6.  Pre-rinsing of clothes in washing machine

Certain people have tried innovative methods to put the waste water from the RO filters to good use. One such utility is for pre-rinsing the clothes before running the rinse cycle in the washing machine.

There are a couple of caveats to this arrangement.

  • This arrangement will work with a semi-automatic washing machine alone.
  • Using water with high levels of TDS can be harmful to the fabric.


We have just seen six uses of wastewater from RO water purifiers. It is natural that you should be checking the TDS levels before using it for these purposes. However, you tend to save a lot of good water when you use waste water from RO purifiers for alternative purposes. This is the need of the hour considering the fact that there is acute water shortage all over the country.

Every drop of water is precious. It is a great initiative if you are able to save as much water as possible.