How Much Water is Wasted in a Reverse Osmosis System?

Reverse osmosis is one of the most effective types of water treatment. It is ideal, especially for people who usually use well water and those living in areas that don’t get municipal water.

Sometimes, the water is full of harmful particles and pathogens hence not safe for drinking. At this juncture, their only savior is an RO water treatment system.

Reverse osmosis removes up to 97% of contaminants and TDs from the water, making it safe for drinking and cooking. It’s a lifesaver!

But now, here comes the challenge. Although RO systems boast a lot of benefits, they have their downsides as well. The major problem is that the systems produce too much wastewater.

Depending on the quality, type and age of an RO system, it can use 3 to 5 gallons to produce 1 gallon of water.

Reverse Osmosis and Waste Water

Reverse osmosis systems use more water than they produce. As aforementioned, producing a gallon of water via the systems results in several gallons going down the drain.

The semi-permeable membrane permeates the clean, pure water to pass through to the storage tank. All the dissolved inorganics, contaminants, and wastewater goes to the drain during the filtration process.

Factors Affecting How Much a Reverse Osmosis System Wastes

Discussed below are several factors that affect how much water your RO system wastes.

1. Water Pressure

When entering the membrane, water pressure needs to be at least 60 psi to push the water through. It is actually the standard for water from municipal water supplies.

If the water pressure is low/not strong enough to push the water efficiently through the system, there will be higher wastewater discharge levels.

2. Poor Maintenance

Reverse osmosis systems require regular maintenance. It could be best if you changed your RO membrane regularly since the older the membrane, the less efficient it becomes. An inefficient RO membrane sends more water into the drain.

3. Reverse Osmosis Brand

Depending on the brand and manufacturer, the efficiency of an RO system differs. For instance, the difference in ratio between wastewater and produced water can vary from 4:1 to 1:1.

Some systems are less wasteful since they use better materials and technology.

How to Minimize RO Waste Water

A. Check your water pressure

To prevent losing water due to low water pressure, consider installing a water pressure pump. You can also get a water permeate pump which actually uses pressure from the wastewater.

The permeate pump hinders the water pressure from the tank from affecting the filter membrane.

As the water pressure from the pure water tank pushes the water via the membrane from the opposite side, it can become less inefficient. It will therefore fail to clean all the water coming from the source.

A permeate pump helps by restraining the pressure and allows the membrane to function more efficiently. When this happens, the ratio of wastewater to drinking water improves.

And to make things even better, the pump doesn’t use electricity. It works in symbiosis with the RO system and uses the power of the wastewater to help the process.

B. Choose a reverse osmosis system brand wisely.

Before selecting a reverse osmosis system for your home, you need to carry out adequate research on different brands and models. Why settle for one that wastes 4 gallons to produce a gallon of water while you can get one that wastes only 1 gallon?

Also, choose the right system according to the plumbing rules and regulations of your state. This will help you evade future problems related to the difference in standards.

C. Perform regular maintenance on your RO system

RO membranes can last for 2 years, but other filters, including carbon, sediment and polishing filters, require replacement every 6 to 12 months.

Replacing the filters and membranes improves the system’s efficiency, and less water goes to the drain.

And when changing the filters, take this opportunity to clean the entire system as well. Taking good care of your RO filter gives it a longer lifespan as well.


Can I use the wastewater from reverse osmosis?

Yes. You can use RO wastewater to water your plants, flush toilets, clean dishes, mop the floor or pre-rinse laundry. However, you cannot use the water for drinking since it typically has a high percentage of contaminants.

Can I use RO wastewater for bathing?

No. This water already contains a lot of contaminants that make it unsuitable for bathing. Only use it for cleaning and watering plants.

What are zero-waste RO systems?

Zero waste reverse wastewater systems are RO systems that produce wastewater, but it’s never flushed down the drain. They are labeled as zero waste because the water is recycled.

How often does an RO system wastewater?

A reverse osmosis system produces wastewater every time you open the RO faucet to pour yourself a cup of water.


Most RO systems waste water ratio is 4:1. In simple terms, the systems purify a gallon of water at the expense of 4. However, one thing for you to note is that these systems don’t waste water more water than you would when showering or cleaning dishes.

It’s also good to note that although these systems waste a lot of water, there are still ways to help you reverse the situation. Also, their benefits outdo the negatives. Therefore, don’t shy away from an RO system just because it wastes more water than other water treatment systems.

Having gone through this post, we believe that you are now better placed to deal with the problem should it arise.

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