Can We Use Reverse Osmosis Waste Water for Washing Dishes

Can We Use Reverse Osmosis Waste Water for Washing Dishes

You have been enjoying the benefits of your Reverse Osmosis (RO) filtration system, but you’ve noticed that quite a lot of water is being wasted to produce your pure drinking water, and you want to put it to use. If you’re wondering whether you can use the RO waste water to wash utensils and how to do it, we’ll walk you through that and more in this article.

You can use reverse osmosis waste water to wash your dishes and cooking utensils. RO waste water can be collected in a holding tank or returned to your hot water line and used for washing and pre-rinsing kitchen utensils. 

RO water rejects about 20-25 gallons for every 3-4 gallons of purified water. This is a lot of wasted water that can be easily used to clean your utensils or do other household chores. In this article, we will explore why RO waste water can be a good choice for washing your dishes and cleaning your utensils in the kitchen.

Read my comprehensive article about reverse osmosis.

Why Should You Clean Your Dishes and Utensils with RO Waste Water

RO systems remove all the salts and minerals from water and flush them out through waste water. The amount of this rejected water can be efficiently utilized to fulfill other household needs. Here is why you should consider using RO waste water for washing utensils:

1.   Cleaner dishes

Reverse osmosis waste water contains a very high amount of salt. Salt is part of many dish-cleaning liquids and soaps. Salt prevents stains and food particles from sticking to your utensils, ensuring cleaner dishes.

The best way to achieve a better clean is to rinse the dirty utensils with the RO waste water and then scrub and rinse them with tap water later.

2.   Less water wastage

The most significant advantage of using RO waste water for cleaning your kitchen utensils is saving water. There are millions of people across the globe that do not have access to clean water for usage and drinking purposes, and you can do your part in saving this precious and scarce resource.

3.   Low water bills

When you are wasting up to 20 gallons for every 4 gallons of pure water, you will end up with a very high water bill. You can use this water to clean your utensils and save up on your water bill.

What Are Some Other Ways of Using RO Waste Water?

Cleaning utensils isn’t the only way to use reverse osmosis waste water cleverly. You can use reject water for other applications throughout your house, such as:

1.   Washing your car

An average car owner uses up to 40 gallons of water every time they wash their car, and if you wash your vehicle at least twice a week, you’re wasting a lot of fresh and clean water. You can use the reverse osmosis waste water for this purpose if you follow the below tips:

  • Use a soft linen cloth instead of a brush
  • Use water at a low pressure

These tips will ensure that the salts and Total Dissolved Solids (TDS), in the reverse osmosis reject water, do not damage the luster of your car.

2.   Flushing your toilets

Did you know that every flush of water takes about 5-7 liters of fresh water down the drain and into complete waste? You can use RO-reject water to flush the toilets across your house.

Make sure you check your toilets for discoloration and damage to the porcelain material. If you wash and scrub your toilet correctly, you can avoid discoloration.

3.   Mopping your floor

Another activity that can waste a lot of fresh water is cleaning your floors around the house with a wet mop. Just add a little fresh water to dilute the minerals, so they don’t damage the floor. You can use RO waste water even if the TDS level is above 2000 ppm.

4.   Watering your plants

Water with high TDS levels, up to 2100 ppm, can be used for irrigation purposes. If the reverse osmosis reject water has a permissible TDS level, and sodium levels are lower than 60%, you should use it for watering your plants.

The trick is to use the RO waste water for a few days and see its effect on the growth of the plants. If you see any stunted growth or yellowing of the leaves, stop using the water. Areas with a municipal water supply can do this more often because the TDS level in these areas is lower.

5.   Washing clothes

RO reject water contains salt that can help remove dirt and stains from fabric. You should use this water to pre-rinse your clothes. Using RO waste water for laundry is good if paired with a fabric softener and a low-pH-level detergent. Read my article about washing your clothes with RO waste water.

6.   Boiling certain foods

You can use RO waste water to boil foods with a shell or case. A great example is eggs because the water cannot directly come in contact with the actual food source.

Tips to Store RO Waste Water

To use the reverse osmosis waste water, you must ensure it doesn’t go down the drain. Here is how you can do this:

  • Connect the waste line to a holding tank in your kitchen
  • Connect the waste line to a larger holding tank outside the kitchen
  • Use a zero-waste RO system that sends the waste water back to the hot water line in your house
  • Install a holding tank above your washing machine and your toilets

Frequently Asked Questions

1.   Can you use RO waste water for cooking?

RO waste water is high in contaminants and salts that are bad for health. RO waste water should not be consumed directly and should also not be used for cooking.

2.   Can you take a bath with RO waste water?

RO waste water can damage your skin and hair because of the high amounts of contaminants and salt present, so it is best not to use it for bathing.

3.   Can you use RO waste water to bathe pPets?

Reverse osmosis waste water, that has been diluted with some natural tap water, can be used to bathe your pets with a high-quality pet shampoo to wash away all the dirt.

Final Thoughts

RO waste water can help you save water for cleaning utensils and other household chores. You need to save water to use around the house, and we hope our tips above can help you do that easily.

Chief Guru

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children. You can also follow him on LinkedIn, Twitter and Facebook.

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