[Matt B]

I just got a reverse osmosis system (man I love craigslist.) I got tired of making trips to get the RO water from the local safeway. But the 2 gallon storage vessel isn't enough for a 10g batch of beer. So right now I'm letting the clean water into a keg that I drained, rinsed, PBW'd and starsan'd through the sanke tap. However, it'll eventually fill up and over flow. So I was wondering if anyone else has done something similar and how you set up an automatic shut off for it.

I'm guessing the normal tank will build up pressure and when the faucet opens, fwoosh, when it closes the pressure of the street water through the RO system will build the pressure back up. I'm not entirely sure this will work with a large 15g vessel, but I'm open to suggestions one way or the other.

Regardless of whether I do let pressure build up, that probably won't be enough to drain enough RO water for a full batch, so I'm going to have to hook up some other system to push the RO water through at a reasonable rate.

And the black hose is the highly mineraled drainage water, and the blue hose is the good water right?

[astrivian]

What brand RO/DI is your system?

The hoses that come out are the same exact thing used for irrigation (at least the ones i have seen are). Therefore, they can attach to the same devices. You can usually find a float valve at a hardware store. You can clip the valve on to the bucket and when the water gets high enough, the valve shuts off the RO/DI unit. HOWEVER, this only works if your unit has a special valve in it that shuts the system off if there is backpressure. Otherwise, the RO part will stop and it will just force all the water out of the waste line.

It is very tricky not to flood your house when using an RO unit. You can make the purified water line really long and put it outside. That way if it overflows it only waters the lawn.

out of curiosity, why are you using RO/DI water to brew? You know you want some minerals in the water for flavoring right? If you are off a well or really hard tap water i can see cutting it with RO/DI water but i wouldn't brew using just purified RO water unless you plan on adding your own salts.

[Matt B]

(Watts) Premier WP5v or something model.

That explains that odd little black manifold that both the good and waste water connect to, I'm guessing that detects the back pressure and shuts off the waste valve. I'll check out some float valves and see if I can rig something up.

You're 100% correct on the mineral part. The water where I live is horrendous, I may as well be in Texas for all the bicarbonates that I have. I usually cut my street water with the RO water, by the time I get the bicarbonates low enough, the other minerals have been lowered a bit too much, and I enjoy tweaking the mineral content for the particular style of beer, so I add back in what is necessary. I also use RO water for yeast rinsing and making batches of starsan (which I may as well throw out as soon as I make a batch and sanitize something with it when using street water.)

[euge]

The black tubing is the effluent yes...

These things are so wasteful but they really help with the beer and tastes pretty good too. I think you're not to exceed 120psi with the water pressure so a modified keg could work as a storage tank.

I want to divert the effluent into a solar still for distilled. The best way would be to have the filters and membrane up in the attic and run the lines to the sink and outside instead of drilling through the wall. I'm already plumbed with the conduit for some of the lines.

I just fill up a few buckets over the course of a day or two before brewing.

[Matt B]

That's an excellent idea. Where'd you get the still?

For the moment, I'm running the waste water to my orange and apple tree. At least it's not going down the drain. if I use close 10g of RO water per batch every few weeks, then the trees are getting plenty of drink. I don't have to worry about plumbing a sprinkler or drip system now!

One thought I had while I (wasn't) sleeping last night is having the waste water go into a bucket with a submersible pump (possibly also solar powered) with a liquid level switch. You could run that through the still, and this is how I'm going to get the waste water out to the line that runs to my trees when the system is in its final place (and figured out how to shut it off when the keg is full.)

[Hokerer]

That's an excellent idea. Where'd you get the still?

Sounds like he doesn't have one yet just would like to get one.  I, too, think a solar still would be a great idea.  In fact, I'd probably bag the RO system altogether - they just waste so much water.

[euge]

I have yet to build the still, though it should only take an afternoon. I'd just run a line out to the plants too but since my base water is softened the effluent also is about 280-320ppm salt water. Not sure what the long-term effects would be.

Also, I've been researching above ground storage tanks to harvest rain water. My backyard floods consistently and deeply prompting an installation of a sub-pump from Harbor-Freight. Now I pump thousands of gallons of rainwater up and out into the street. My neighbors also are affected but since the lay of the land drains into my backyard the pump takes care of their flooding  too. The neighbors are ever so grateful and my backyard's grass looks better.

Imagine having pure rain-water just for brewing and the lawn, plants etc...

Here's a few pics. Number one is the first time I saw it flood, and the water used to get 12" deep back there at times until the pump was installed:

[Matt B]

Holy crap. I haven't seen rain like that since I left PA. We don't get nearly that much here in Cali. But enough that a friend of mine did install an underground storage tank, prompting me to think of doing the same. He uses it to water his garden during the zero rain late spring, summer and fall. Not sure how long it'll actually last him though.

I would avoid using the salinated water on the plants as well.

Does anyone know what happens when you run the effluent (new word for me) water back through the RO system? does it waste just as much water just increasing mineral concentrations, or does it waste more water based on the increased concentrations?

[Kaiser]

The tank that comes with R/O systems is a bladder tank. Those tanks have an air bladder inside which gets compressed by the water pressure. It will stop filling when the pressure inside the tank gets to high for the R/O system to overcome. Because of the air bladder you will not be able to fill all of the 2 gallons of your tank.

One option is to buy a bigger tank, but they are expensive.

The float switch should work and so should modifying a keg. You may be able to make a keg work like a bladder tank by not venting it when filling it with water. But that allows you to collect only 2-3 gallons. Seems that a large vessel and a float switch is a more attractive option.

The black manifold is a pressure booster that uses some of the effluent pressure to boost the pressure of the raw (i.e. incoming water). The system I'm using has one too.

The recovery rate, which is the amount of R/O water that is "recovered" from the input water also depends on the temporary hardness and pH of your water. If the pH is high and your have a lot of calcium and bicarbonate there will be calcium carbonate precipitation near the membrane due to the increased calcium and bicarbonate concentration. As a result it is beneficial to run a R/O system after a water softener. This only makes sense if you already have a water softener.

If your problem is high temporary hardness, as opposed to high alkalinity paired with sodium, you may also be able to use slaked lime to treat your water. There is no or only little water waste associated with that technique.

R/O systems can be cascaded to get a better recovery rate. I think many commercial systems do that. But the cost keeps increasing while the actual return on investment decreases.

Kai