RO Water and the downsides?

[Buckeye_Hydro]

Hi guys - I just read through this thread for the first time. There are a fair number of misconceptions, misunderstandings, and only "kinda-correct" info in this thread re RO systems. We're happy to talk with anyone considering a system.

Russ
513-312-2343

 

[Buckeye_Hydro]

Well how long will it take to clog the membrane? I'm not interested in purchasing a softener system also, is it necessary?

Here's the low-down: In general, the more expensive the replacement membranes are, the more it makes sense to pretreat as appropriate (e.g., soften) the water sent to an RO system. On commercial RO systems where replacement RO membranes can be hundreds of $ or more, and where use is heavy, softening the feedwater is commonplace. On residential-scale systems (typically 150 gpd or less) that use 1812 membranes (1.8" in diameter and 12" long, nominal), replacements are relatively inexpensive (~$30 to $55), and people are much less likely to soften the feedwater due to the initial expense and required upkeep/maintenance of the softener (primarily adding salt pellets).

But - one other thing to consider - if your water is hard, you may want to consider the whole-house benefits of a softener. Not only will your RO membranes last longer, but you'll be able to reduce the amount of water sent to drain by your RO, you'll reduce the amount of soap and detergent you use, and you'll protect your other plumbing fixtures (hot water heater, faucets, etc.) as well.

Brewers often have a knee-jerk aversion to softeners because they've heard softened water will be higher in sodium. But that sodium issue is more than adequately address by the RO process.

Russ

 

[mabrungard]

I'm not a huge advocate of ion-exchange softening, but it is useful in some cases. One area that softening is especially useful for, is your home's hot water system. Feeding softened water to just the water heater can significantly improve the heater's life and performance. My house had the entire internal water system hooked to the water softener, but I replumbed it to feed only the hot water heater. I'm glad I did.

By the way, I feed my RO from the softened water circuit.

 

[jcav]

That's good to know ^
I have been contemplating getting a R/O system, as I have been going to the grocery store to get my R/O water from the Glacier machine.

John

 

[mongoose33]

I'm not a huge advocate of ion-exchange softening, but it is useful in some cases. One area that softening is especially useful for, is your home's hot water system. Feeding softened water to just the water heater can significantly improve the heater's life and performance. My house had the entire internal water system hooked to the water softener, but I replumbed it to feed only the hot water heater. I'm glad I did.

By the way, I feed my RO from the softened water circuit.

Last year we had to replace our water heater, which had been fed only softened water for its entire service life.

Know when it was installed? 1992. I think a 25-year service life is a reasonable testament to the value of using softened water in a water heater.

We have softened water feeding all faucets in our house except for the cold water kitchen faucet. That's where I draw my brewing water which is then cut w/ RO.

 

[Buckeye_Hydro]

At a minimum, when a whole house softener is installed, the outside garden hose bibs are excluded from the softening.

Russ

 

[The_Bishop]

Hi guys - I just read through this thread for the first time. There are a fair number of misconceptions, misunderstandings, and only "kinda-correct" info in this thread re RO systems. We're happy to talk with anyone considering a system.

I know this is you main line of business, but I'm always up to learning more. If I've given out incorrect info please let me know. Maybe consider putting together a FAQ for RO systems?

 

[ajdelange]

Well how long will it take to clog the membrane? I'm not interested in purchasing a softener system also, is it necessary?

That depends on how hard and alkaline the water is and the design recovery rate. The answer you want, of course, is 'it takes forever' and it does as long as the concentration of the 'limiting salt' (which in most cases is going to be calcium carbonate) in the concentrate is less than the saturation level under the operating parameters of the system and the nature of the water. The cheap under the sink units solve this problem by operating at very low recovery. The installation instructions will usually tell you what the maximum hardness of the water that is fed to these units should be. I think its about 17 grains per gallon. That's 17*17.1 = 290 ppm as CaCO3. That's more hardness than most people encounter and that's really the temporary hardness limitation. Permanent hardness does not result in clogging (unless calcium sulfate becomes the limiting salt but I think that would be pretty unusual). I guess I should note that my recollection that the undersink units can handle up to 17 gpg is a bit suspect given that the conversion to ppm is 17.1 but I really do think the number is around that. Thus most brewers can simply buy one of these units and sail on with little fear of having a clog or simply replacing a membrane cartridge (which isn't that expensive for these small systems) as necessary.

But whatever it is that makes us want to home brew makes many of us want to tinker and some home brewers are also tree huggers and appalled that every gallon of water that goes into their mash tun sends 4 down the drain. Some assuage their guilt by saving this water for laundry or watering their lawns (but a real tree hugger doesn't water his lawn, does he). And some put pumps in front of their membranes and restricting valves after thus increasing recovery, wasting less water, getting more permeate faster and increasing the chance of clogging. One can, of course, simply keep changing out membranes as the alternatives are to accept lower recovery or feed the thing with softened water. If your water is wicked hard as you suggest it is likely that you would have a whole house softener anyway as really hard water is a big PITA WRT boilers, laundry, dishwasher and hot water heater.

An under the sink unit is what it is but if you buy anything else a good dealer will ask you for a water analysis and let you know if there is a potential problem. If you want to kluge something yourself you are on your own. The limiting salt calculations are not difficult and I can post them if you want me to.

 

[ajdelange]

I'm not a huge advocate of ion-exchange softening,

This suggests that you prefer an alternative but the rest of the post suggests that you simply are not a huge advocate of softening by any means. Could you clarify and in particular, if you are saying you prefer an alternative method, tell us what it is?

One area that softening is especially useful for, is your home's hot water system. Feeding softened water to just the water heater can significantly improve the heater's life and performance. My house had the entire internal water system hooked to the water softener, but I replumbed it to feed only the hot water heater. I'm glad I did.

I've done pretty much the same thing. I just took the softener out in the house. When I replaced the boiler based heating system with a water to water heat pump I also tossed the hot water heater in favor of an instantaneous hot water heater which provides the DHW and backs up the heat pump if it fails or it just gets to cold for it. The 'Combi - Boiler' is as sensitive to hardness as any other type but when the exchanger efficiency drops you get an error message (sent to your smart phone, of course) and you then just circulate some vinegar to remove the lime deposit. Tip: monitor the pH of the recirculating vinegar. It will rise as long as it is removing CaCO3. When there is no more CaCO3 to dissolve the pH stops rising and you are finished.

By the way, I feed my RO from the softened water circuit.

In the brewery there is a ion exchange softener but it feeds only the RO system and the boiler.

So I guess I too would have to say that I am not a big fan of softeners in general. But the calcium part of my temporary hardness is not high enough (around a mEq/L) to be a problem for the laundry etc. The Combi has gone a year without a problem But the brewery boiler and RO unit get softened water and the heat pump exchanger loops, both ground and air handler, are filled with RO plus glycol and corrosion inhibitors. The contractors thought I was nuts but then a lot of people do.[/QUOTE]

 

[ajdelange]

I wonder if a membrane auto-flush kit would mitigate mineral build-up.
I'd definitely contact Russ @Buckeye_Hydro about such issues...

Yes, membranes can be cleaned of mineral and biofouling. Follow the manufacturers instructions!

Automatically? I suppose something could be put together and perhaps has been.

 

[ajdelange]

Last year we had to replace our water heater, which had been fed only softened water for its entire service life.
Know when it was installed? 1992. I think a 25-year service life is a reasonable testament to the value of using softened water in a water heater.

After I took the softener out of the house water heater life dropped to about 10 years. In those ten years how many times did I flush and treat with acid? How many times did I inspect and replace the anodes? 0 and 0 so I expect that I deserve what I got. But I really think the answer is the combi boilers which have essentially 0 recovery time, save you lots on energy, are much smaller than the tank type and tell you when they need to be cleaned. Not only tell you, but force you to clean them as they won't produce hot water if the efficiency gets low enough. Of course they have finite lifetimes too but I have no idea what they are. I had one fail but it was in a house I bought and I don't know when it was installed.

 

[Buckeye_Hydro]

aj - That quote refers to an auto flush valve on the concentrate line - a solenoid with an internal timer that bypasses the flow restrictor when open.

http://www.buckeyehydro.com/membrane-flush-kit/

 

[day_trippr]

Yes, membranes can be cleaned of mineral and biofouling. Follow the manufacturers instructions!
Automatically? I suppose something could be put together and perhaps has been.

It has, and I installed one of these with the flush kit with 36gpd restrictor recently...


Cheers!

 

[Buckeye_Hydro]

We always recommend the auto flush valve w/o the integrated flow restrictor. That way if your tap water changes (seasonally for example) or you change the capacity of your membrane, you can replace a $4 flow restrictor rather than replace the entire expensive solenoid.

Russ

 

[ajdelange]

How about switching the input to the system from the feed water source to the output of the pressure tank for a short period before shutting the pump off? This means that the system awaits its next command with nothing but RO water sitting in it. No possibilty of deposition of anything in prefilters, pumps, on membranes...from concentrate or even feed water sitting in there no matter how nasty the feed water (in my case the potential problem is silica). I'll have to think about that.

 

[Buckeye_Hydro]

Yes - this is called a permeate rinse, or a permeate flush. It is a good idea, but typically a level of complexity a tad too high for the average residential scale user. The process can be automated - typically on commercial systems where the cost is significantly higher. I'm guessing I could see one in your brew room about a month from now

Russ

 

[ajdelange]

Tempting, but at the moment I don't need another project! But I do have a couple of timers and some spare ice cube relays....

 

[millsbrew]

You will be better off using distilled water and building your water with that. It is dirt cheap and there is no upkeep. That is what I do. The cost of that system will buy years of distilled water not to mention all of the waste water an RO system generates.

I’d strongly disagree. I was paying $2 per gallon of distilled water. Using 11 gallons per batch on average that’s $22 per batch. My system cost $175. Paid for itself in under 8 batches. And prices appear to have come down. Check out Bulkreefsupply.com.

 

[Transamguy77]

At this point I'm going to be doing some more research and get in contact with Russ about my options. At the moment I rent but after speaking with my neighbor he told me that Culligan offers a softener service and the my house already has the hook ups so this changes things a bit.

I feel like we went off topic a bit from the OP's original question and not sure if it was really answered but I think there was some good info on RO systems in general so I hope rhat was a help.