RO Filter Drain

[Ronaldo38]

My water softener is in the basement directly under our kitchen. As you know Reverse Osmosis water filters waste about 3 to 4 gallons of water for each gallon they make. So, is there any reason I cannot drain that "waste" water into my water softener tank? That "waste" water is actually pretty clean.
TIA for some expert advice.

 

[Bannerman]

Reverse Osmosis water filters waste about 3 to 4 gallons of water for each gallon they make.

Don't think of it as waste. That drain flow is necessary to flush away the solids that would otherwise collect on the RO membrane and eventually prevent its operation.

Your drain flow volume could be reduced by installing a permeate pump onto the system as that will result in the storage tank filling faster, thereby reducing the run time for the RO unit.

Do you consider the fuel used to power your car as wasted?

any reason I cannot drain that "waste" water into my water softener tank?

Do you mean into the brine tank?

The water added to the brine tank is a specific quantity so as to dissolve a specific amount of salt which corresponds to the amount of capacity that is to be regenerated each regeneration cycle. Adding an nonspecific quantity of water to the brine tank, would likely result in considerable wastage of salt assuming the water added will be more than is needed. Each 1 gallon added will dissolve 3 lbs salt.

Just because the RO drain water appears clean, does not signify that it is, depending on the contaminants and minerals that are being removed by the RO membrane.

 

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[Ronaldo38]

Don't think of it as waste. That drain flow is necessary to flush away the solids that would otherwise collect on the RO membrane and eventually prevent its operation.

Your drain flow volume could be reduced by installing a permeate pump onto the system as that will result in the storage tank filling faster, thereby reducing the run time for the RO unit.

Do you consider the fuel used to power your car as wasted?


Do you mean into the brine tank?

The water added to the brine tank is a specific quantity so as to dissolve a specific amount of salt which corresponds to the amount of capacity that is to be regenerated each regeneration cycle. Adding an nonspecific quantity of water to the brine tank, would likely result in considerable wastage of salt assuming the water added will be more than is needed. Each 1 gallon added will dissolve 3 lbs salt.

Just because the RO drain water appears clean, does not signify that it is, depending on the contaminants and minerals that are being removed by the RO membrane.

Thanks for the speedy replies. I'm not at all knowledgeable about water softeners, so I thought dumping the R.O. drain into the brine tank would work well. I'll dump it overboard until I can install a permiate pump.
Thanks again for your help.

 

[Reach4]

There could be a method where your idea would work great, but not with the common systems.

There is a system where the water from the RO unit is fed into the hot water, with a pump, for showers etc. Watts call it their "Zero Waste" system. Their "Zero Waste" Reverse Osmosis Retrofit kit #501026 will let you convert an existing RO, but it is not cheap.

 

[ditttohead]

And it is not zero waste.. it just converts the "waste" water into wasted electricity, more complex system design, and more potential for leaks in the future.

If you are running a softener, you can change the flow restrictor on your ro system to a much smaller one. Typically 1:2 is considered acceptable... but... this is a 2 hour classroom session on residential RO system efficiencies, design, consideration, cost analysis etc...

If you are on a municipal supply then the water going to drain is usually processed at the sewage treatment plant then sent down the river to the next town anyway so the water is not really wasted, it is simply recycled.