Rejection rates for RO unit.

Anyone figure out how much water they're using with their RO unit?
I have a 75 GPD... When I make water waste goes down a drain. I've been looking on the internet to see how much total water is being used to make 75 gallons for instance.

 

Great question, was wondering about that myself.. best I could come up with quick was this bit of info....

Disadvantages of reverse osmosis units

RO units use a lot of water. They recover only 5 to 15 percent of the water entering the system. The remainder is discharged as waste water. Because waste water carries with it the rejected contaminants, methods to re-cover this water are not practical for household systems. Waste water is typically connected to the house drains and will add to the load on the household septic system. An RO unit deliver-ing 5 gallons of treated water per day may discharge 40 to 90 gallons of waste water per day to the septic system.

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I have also read that many new RO units are much more effecient, guess you would have to check with your manufacturer to determine what the reject % is for your model.

 

yeah but there is a million variables on this, there has been tons of people try to figure it out but every ro/di is different and every house is different, there will be a lot of waste water but there is no good solid answer

 

That why mine is hooked up to my rains barrels in the summer and my sump outlet in the winter. I also use the waste to water my indoor plants. The amount of waste varies due to water pressure, age of filters and other factors.

 

I think a typical ro/di is 3 to 1 ratio or 4 to 1, so 3 gallons wasted for every 1 gallon good water, I've seen some list 1 to 1 ratios but can't remember where. Some people collect the water and use it for there gardens or watering there grass.

 

There are very low rejection rate units, but they are very expensive, $800 on up. My 100GPD will spit out ~4G for every 1G it makes. Egger brought up something good, I may collect the water and use it to water my grass. My water bill goes up quite a bit when I make a lot of water. It really went up when I refilled my 150G tank recently.

 

4 to 1 is what I have heard. Ask the H2O_guru from Air Water & Ice he will know.

 

Wow, I never realized it was that high. Good thread!

 

ive been told 3 to 1, they have a nice unit by spectrapure that makes 2 gallons of good water per one waste but big money.

SpectraPure MaxCap UHE 100 from Salty Critter - Your Saltwater Specialists

 

A few things you can do to make them more efficient are keeping the water going in around 70 to 75 degrees (not using water from your hot water heater) and a boost pump. Also you can run dual membranes like the one filter guys sell.

Dual Membrane Test results

Water Saver Test Results