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Is Reverse Osmosis Wasteful?

by Mark Timmons May 10, 2011 70 Comments

"Don't even talk to me about reverse osmosis" said the woman on the telephone. "They waste too much water and I want to be conservative with our water resources!"

That is something I hear quite frequently and frankly, I don't understand it. Oh, I understand wanting to be conservative with our natural resources, but that same woman was driving 7 miles to town and back to get bottled water which probably was made by reverse osmosis anyway! Let's pollute the air and waste fossil fuel, but dad-gumitt, I won't waste a drop of precious water! Of course that is crazy, but let me put this in perspective. A reverse osmosis system wastes about 4 gallons of water per gallon made. If you use 3 gallons a day for drinking, cooking and internal consumption, that means you will waste about 12 gallons, making a reverse osmosis system about 25% effecient! However, US Water Systems are able to reduce water waste by up to 80%

Is that bad? Like I said, let me put it in perspective. Do you have a washing machine? Do you have a dishwasher? Why do you have a washing machine and dishwasher? Well, obviously it's to get your clothes clean and to get your dishes clean and sterilized. How efficient is your washing machine? A reverse osmosis system is 25% efficient. A washing machine and dishwasher uses electricity and hot water (which takes energy to heat) and WASTES EVERY GALLON OF WATER THEY USE.

A reverse osmosis system is not nearly that wasteful - no electricity and no wasted energy with heated water. You have a washing machine to get your clothes clean. You have a dishwasher to get your dishes clean. You think nothing of wasting water and energy to get your clothes and dishes clean, and yet you don't want a reverse osmosis system that is 25% efficient to get your water clean? Are you nuts? How long can you live without clean clothes? You might stink, but it won't kill you! How long can you live without clean dishes? You get the picture? Your body uses water to cool it and eliminate waste, but you are unwilling to waste a little water to clean your water for internal consumption? The water you drink sustains your life? You'll waste water to clean your clothes and dishes, but not to clean your water? You must be kidding!

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70 Comments

May 20, 2011 Karon

Help! My dishes are coated with white ‘crud’ and cannot get them clean. Dishwasher repair advised not dishwasher but ‘hard water’ problem. Contact Mermaid Water to discuss as they installed Kinetico 2100F series whole house water filter system in October 2010. Previously had Rain Soft Water Filter System in home since 2000. Due to problems, poor service, etc., replaced it with the Kinetico.
I did not have the dishwashing problems until February 2011. Inquiries to Mermaid(Kinectio Dealer) advised me it was due to dish washing detergent formula changes. Basically, advised to purchase water softener or wash dishes by hand!

Had water tested by Lab – results: Hardness as CaCO3-EDTA – 179 mg/L RL 2.

Spent hours online reviewing all these systems and an more confused than ever!

Home – well water & septic tank – 3 baths.

Please any suggestions, comments, etc., are needed. Thannks

May 22, 2011 mark

Karon,

Try a product called Lemishine and let me know how it works.

May 23, 2011 KG

Are you an idiot?

May 23, 2011 mark

KG,

Are you? I just thought I’d ask.

August 12, 2011 Darcy

What about something like this?

http://www.watts.com/pages/_products_details.asp?pid=7257

August 12, 2011 mark

Darcy,

I have not been impressed with that model. We are a Watts distributor and do not sell it. Check valves, pumps, re-injecting the water into the hot water, etc. The cure is worse than the disease.

February 26, 2013 Dave

This article is written in a very belligerent tone. I wanted to learn about how much water is wasted in the reverse osmosis process and, if this article is correct, 75% is truly wasteful indeed. I have municipal water that was of such poor quality that the private company was forced to turn over operations to a state utility agency until such time as it can be turned over to a county or city utility. Customers complained for 13 years before the takeover and the result of the utility’s and the state’s efforts to improve water is one of the highest water rates in the state. We replaced toilets with 1.28 Gallon or less systems and installed very restrictive water saving aerators at the sinks and low volume shower heads. We put in a shallow well to water our vegetable garden and removed 100% of our turf grass (to the irritation of the home owner’s association but with the backing of Florida state law). Each month, our family of four uses about 5,500 – 6,500 gallons of water and our combined monthly water/sewer bill is between $90 and $120. At these rates, any appliance that “wastes” 75% is a problem for my family. Contrary to the author’s argument, we all use 100% of the product resulting from each cycle of the washing machine or dishwasher so the only question of waste is, can we do the same with less water and less electricity? Modern, high efficiency appliances use less water and energy than their old counterparts. We’re still working up to the appliances and doing the math for the return on that investment. Maybe then, we can afford to throw out 75% of our drinking water.

The Water Doctor Replied:

Dave,

The tone wasn’t belligerent – it was frustrated because of people like you who want to compare apples with oranges. The blog was written from the perspective of point-of-use drinking water, but you extrapolated that into what you use in your whole house. I wrote this:

“A reverse osmosis system wastes about 4 gallons of water per gallon made. If you use 3 gallons a day for drinking, cooking and internal consumption, that means you will waste about 12 gallons, making a reverse osmosis system about 25% efficient! Is that bad?”

So, if you use 3 gallons of water a day, that would equate to 360 gallons per months (12 × 30 days). This is truly insignificant, especially if you are burning fossil fuel to drive to the store and buy bottled water whose bottles end up in the landfill. However, you don’t have to waste this water. You can put it on your lawn or garden, so there is NO WASTE!

The point is: people waste a lot more water for less noble purposes. What is more important than clean, safe drinking water? Reverse osmosis removes the largest spectrum of contaminants of any water treatment process. If you settle for less, you will be the filter. I prefer that the reverse osmosis system be the filter, not me!

If you are that conscious about saving water, you will have no problem recovering every drop that goes down the drain.

February 26, 2013 Mike

Yes, the tone is belligerent, but I suppose the 75% figure is accurate. My plan is to drain the water outside of my home and use it to water plants. This won’t work on the coldest days, I know. Also, you can buy a system that puts the waste in your hot water line.

September 27, 2016 Mary

I was hoping for information, too. But I also found the post to be belligerent and unhelpful. YOUR comparisons don’t hold up and sound sadly defensive. I’ll go elsewhere to actually gain some perspective and information about RO water and household usage. I think Dave’s right! Using water to wash clothes and dishes is not wasted. Especially if you use a water wise system…which I do. AND only wash FULL loads. Not the same at all. For the most part, water that comes out of the tap (whether well or municipal) is some of the cleanest and purest water in the world. Very few of us NEED to RO it. And turning 4 gallons of water into 1 is the definition of waste. AND I have an RO system so I am not coming from a place of having no idea what I"m talking about, but I use it very carefully, thoughtfully and sparingly. I hope we all do because water is beyond precious…along with our air and natural environment. They all work together to keep us happy and alive!

September 27, 2016 Mark Timmons

I am sure you can claim ignorance as an excuse for your belligerence. They say ignorance is bliss…

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