Wasted water from RO system

[brick_haus]

I was reading palmers Water Book and he states that on a typical home RO water system, 4 gallons of waste water are produced for every one gallon of RO water.
So, being the OCD type, i disconnected the hoses from my system and sure enough, I got one gallon of RO water and four gallons of water that would have otherwise gone to the drain. So I used it to water my plants (hope they like sulphur!!!)

I'm looking for a better systen that does not waste so much water. What are you guys using? I use ~20 gallons per week just for strike/mash/sparge.

Thats 80 gallons wasted!

 

[Natdavis777]

I pick mine up at the store. I let them eat the cost of wasted water and pass the savings down to me

Seriously though, it costs me under 10$ for a 15gal refill of RO water

 

[pvtschultz]

I have a private well and septic system, so it just goes back into the ground where it came from to be used again.

Watering the grass, garden, trees, and other plants would be the best/easiest solution to me. Maybe pump it out to a pool/pond?

 

[JoshuaW]

If you already do those things (watering the plants, yard, etc) then it really isnt a waste, assuming the high concentration of things you are filtering out doesnt do them any harm. You could build a rain barrel to serve as a storing point for your RO water with the added bonus of collecting rain to dilute it at times. I have seen some impressive drip irrigation systems run off of rain barrels.

I know very little about RO, but would it be possible to filter it a second or third time? I would imagine you would need a pump to get it at the right pressure, its a thought.

 

[ajdelange]

The systems that one buys for under the sink installation are designed to have a pretty good lifetime using input water that is fairly hard and alkaline. To do that they are set up to have terrible (18 -20%) recovery. Recovery can be improved by slight re-design. You will need a restrictor valve in the brine line and a pump (a pretty good one) in the feed line. By pumping the water in and restricting its (brine) outflow you increase the pressure across the membrane so more water flows through and less out the brine line. To maximize the pressure difference eliminate the pressure tank and collect to atmospheric pressure.

Higher recovery means more concentrated brine and thus greater liklihood of mineral deposit on the membrane which will clog it and shorten its useful life. The problem mineral is, 9 times out of 10, calcium carbonate so if you do make mods like the one I described you must feed the system with softened (calcium removed and replaced with sodium) water.

As to what I do: I have a system with a pump, an adjustable restrictor valve, pressure gauge and flow meters for permeate and concentrate. I adjust the restictor until I get the ratio of permeate to concentrate I want. I operate at 33% recovery (2 gal wasted per gal permeate) because, though I feed softened water, I do have appreciable silicate. The concentrate just goes down the drain.

With a properly configured system (involving feedback of concentrate to the input*) recoveries of up to 80% are achievable at the cost of somewhat degraded rejection.

*That should answer the question about filtering it a second time posed in #4.

 

[ajdelange]

*

 

[jimyson]

I pick mine up at the store. I let them eat the cost of wasted water and pass the savings down to me

Seriously though, it costs me under 10$ for a 15gal refill of RO water

I do the same. I pay .39 per gallon and it has UV on it. When I brew, I bring in 5 gallon BPA free jugs to fill. I also fill up around 10 gallons a week in gallon glass jugs for personal consumption.

I tried the RO route and wasn't as happy with the taste and waste. I ended up returning the unit.

 

[LandoLincoln]

I was reading palmers Water Book and he states that on a typical home RO water system, 4 gallons of waste water are produced for every one gallon of RO water.
So, being the OCD type, i disconnected the hoses from my system and sure enough, I got one gallon of RO water and four gallons of water that would have otherwise gone to the drain. So I used it to water my plants (hope they like sulphur!!!)

I'm looking for a better systen that does not waste so much water. What are you guys using? I use ~20 gallons per week just for strike/mash/sparge.

Thats 80 gallons wasted!

It's not "wasted." It's returned to your municipal water treatment plant. You'll see that same water come back to you in a week or so. Minus a few things.

 

[jimyson]

It's not "wasted." It's returned to your municipal water treatment plant. You'll see that same water come back to you in a week or so. Minus a few things.

You'll also see an increased water/sewer bill for most city water.

 

[LandoLincoln]

You'll also see an increased water/sewer bill for most city water.

What?! The city charges me for processing water?! WHY DIDN'T ANYONE TELL ME THIS BEFORE?!

 

[Yooper]

My RO system is set up in my laundry room, also known as 'the brewery'.

Sometimes I send my waste water to the washing machine, and add some borax to the water as a 'softener', which I do anyway for heavily soiled loads.

 

[blizzard]

What?! The city charges me for processing water?! WHY DIDN'T ANYONE TELL ME THIS BEFORE?!

Don't you see it in your bill every month?

 

[LandoLincoln]

Don't you see it in your bill every month?

I don't actually have any running water in my house, per se. I have a hose that runs from my neighbor's outside spigot. The water pressure is rather low, but you can't beat the price.

 

[brick_haus]

Thanks for the replies. I'm already bypassing (eleminating) the pressure tank. Restricting the concentrate is a good idea that I have also considered, but not yet implemented. Re-running the concentrate is a good idea, but it would be a manual operation requiring too much time.
I do not have a SAC unit at the house, so membrane replacement cost is probably going to get pretty high.
I have many uses for the concentrate, lawn, garden, fruit trees etc. I usually buy water from the "water store" for $.25/gallon but want to have water on demand, and I have this little RO system laying around collecting dust.
Just wondering what y'all are doing and if there might be a better way.

 

[brick_haus]

My RO system is set up in my laundry room, also known as 'the brewery'.

Sometimes I send my waste water to the washing machine, and add some borax to the water as a 'softener', which I do anyway for heavily soiled loads.

If your concentrate smelled like mine does (sulphur), you probably wouldnt want it anywhere near your laundry!! I think the roses will like it though.

 

[ajdelange]

Re-running the concentrate is a good idea, but it would be a manual operation requiring too much time.

You'd want to plumb that from a tee before the concentrate restrictor valve (so it will be at high pressure), through a second restrictor valve to control its flow to another T at the inlet to the pump. The recovery and rejection depend on the flow rates so you need to be able to monitor those.

 

[seigex]

Just for reference, I got a call from my water company to let me know that I had a water spike that resulted in me losing 750 gallons of water in a single day, and that I need to find the leak or broken pipe. Nevertheless it scared the crap out of me, and I started imagining that I would be getting a several hundred dollar bill from them.

I asked her what my damage was going to be after my heart started beating fast, and she filled me in that 750 gallons was 100 cubic feet, which would cost me $4.20.

So if I were to lose 4 gal for every 1 gal with RO, I would still be able to brew with 150 gallons of RO water for $4.20 or $0.028 per gallon.

 

[ScrewyBrewer]

I got really tired of running to the local food store hoping they had enough distilled water in stock for me to create my brewing water profile on brew day. So after a lot of research and comparison shopping I bought the SpectraPure CSP RO 90-AF reverse osmosis water filtration system and hooked it up.

One of the more important features of this unit is that it uses just two gallons of water to produce one gallon of pure RO water, when compared to other RO filters on the market that is substantially less waste water per gallon of purified water. The RO filter runs on typical residential water pressure, if your water pressure is below 40 psi you will need to buy a booster pump to increase the water pressure. The nominal specifications for the model I bought are 60 psi water pressure at 77F and 500 ppm TDS.

 

[LandoLincoln]

Just for reference, I got a call from my water company to let me know that I had a water spike that resulted in me losing 750 gallons of water in a single day, and that I need to find the leak or broken pipe. Nevertheless it scared the crap out of me, and I started imagining that I would be getting a several hundred dollar bill from them.

I asked her what my damage was going to be after my heart started beating fast, and she filled me in that 750 gallons was 100 cubic feet, which would cost me $4.20.

So if I were to lose 4 gal for every 1 gal with RO, I would still be able to brew with 150 gallons of RO water for $4.20 or $0.028 per gallon.

Let's see here...I use about 12 gallons of RO water a month for my brewing on average and that means I have 48 gallons of waste water a month from my RO system...that's a buck ninety-two a month spent on waste water! Egads!

 

[seigex]

Let's see here...I use about 12 gallons of RO water a month for my brewing on average and that means I have 48 gallons of waste water a month from my RO system...that's a buck ninety-two a month spent on waste water! Egads!

I'll do you one better, it's actually $0.34 for the entire 60 gallons (assuming $4.20/hcf or 750 gallons)

60/750 = 0.08
$4.20 * 0.08 = .336

now multipy it by .8 (80% waste water) .. you lose $0.27 a month and the beer water itself (aside from waste) only costs you $.07 a month.

To put it a little more in perspective. If a shower head's flow rate is 2.5gpm .. that means a 15 minute shower is 37.5 gallons, or a 20 minute shower is 50 gallons. So if you take that long of a shower, you will use more water in two days worth of showers than you use for beer, including waste water each month.

 

[brick_haus]

Let's see here...I use about 12 gallons of RO water a month for my brewing on average and that means I have 48 gallons of waste water a month from my RO system...that's a buck ninety-two a month spent on waste water! Egads!

A penny saved is a penny earned.

 

[jimyson]

What?! The city charges me for processing water?! WHY DIDN'T ANYONE TELL ME THIS BEFORE?!

I know, it's crazy!

 

[blizzard]

As someone who has worked with industrial RO systems, it's crazy to me that the best the residential market offers is 33% recovery.