RO vs RODI

I've been doing my reading on water and need help setting up a home system. My tap water is horribly hard and full of chlorine. So we put on a water softener years before I was brewing. Since going AG 2 years ago, I've started using distilled water from the store, and adding my salts with the help of Bru'n Water. In an effort to save $10 a brew day and a trip out of the house, I'm going to buy an RO water system and store the water in a large food grade plastic tub.

So my question for everyone, is adding a de-ionized membrane to an RO system worth the expense? Or should I just get a Wards lab test on my water from my RO system? I've read that RO will be close enough to be considered distilled for most brewing applications. I'm making 6 gallon batches of brew for me and my friends/family, not to be sold to the world, so I'd like to be practical, while still having good water for brewing and fermentation.

Thanks in advance.

Sorry, I don't have an answer to your DI membrane question. But I do have to ask--$10 for distilled water each brew day? You must be buying gallon jugs of it from the store. Do any of your stores sell RO water from a bulk dispenser? The supermarkets here and Walmart have it for less than 40 cents a gallon. BYO containers.

Something to consider before spending the $$ on a filter system.

millsbrew said:

So my question for everyone, is adding a de-ionized membrane to an RO system worth the expense? Or should I just get a Wards lab test on my water from my RO system?

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You should get the Ward Lab's test but on your feed water to see if it needs to be softened before going to the RO unit. The small home units usually set recovery rate (the percentage of feed water that comes out as RO) at, typically, < 20% so that you can go pretty hard before a softener is required but even so a system fed with softened water will last longer.

Another reason for the Ward Lab's test is to get a rough idea as to what the ion concentrations are likely to be in the permeate. This is generally done by assuming 95% rejection of all ions. Some manufacturers provide data on the rejections for specific ions. Most will conclude, based on this analysis, that the permeate is low enough in ion content that no further processing is warranted. IOW the answer to your question is that adding the ion exchange parts of the system is not necessary in the vast majority of cases.

Thanks AJ. I tested the house water post-softener and it is basically extreme amounts of chlorides and sodium as I expected. I will be testing my post-RO water as well.

Cheers.

A post RO test is, IMO, kind of a waste of money. You will, again IMO, learn more from a pre softener test. From that it's a simple matter to estimate what post softener and post RO tests will show. If you don't care about the few bucks involved then by all means do a post RO test too.

millsbrew said:

So my question for everyone, is adding a de-ionized membrane to an RO system worth the expense?

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No it's not. The RO membrane will remove 95-98% of impurities. The remaining 2-5% that the DI would remove is insignificant.

I agree that including deionizing media on the RO output is totally unnecessary for brewing use. Its just one more thing to pay for.

Instead of the Ward Labs test, purchase a TDS meter. They can be purchased for pretty cheap and they'll help you keep an eye on how well your RO system is working and when it may be time to change out the filters.

MaxStout said:

Sorry, I don't have an answer to your DI membrane question. But I do have to ask--$10 for distilled water each brew day? You must be buying gallon jugs of it from the store. Do any of your stores sell RO water from a bulk dispenser? The supermarkets here and Walmart have it for less than 40 cents a gallon. BYO containers.

Something to consider before spending the $$ on a filter system.

Click to expand...

Depending on a supermarket for RO water is like depending on a HBS for grinding your grain. Don't be surprised if you get less than optimal results.

LandoLincoln said:

Depending on a supermarket for RO water is like depending on a HBS for grinding your grain. Don't be surprised if you get less than optimal results.

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Strange analogy.

Is there some data available that shows an advantage to home-filtered RO water vs. store-bought RO water?

MaxStout said:

Strange analogy.

Is there some data available that shows an advantage to home-filtered RO water vs. store-bought RO water?

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With a home-based RO system, you know for a fact how often the filters are changed and how often the system is used. Grocery store systems, not so much.

Maybe someone who has a TDS meter and uses grocery store RO systems can chime in.

Oh, and the instructions for my Hach Pocket Pro+ pH meter state to rinse off the sensor and cap with deionized water. So deionized water may be useful for a brew day. I've been cheating and just using RO water to rinse it off with.

I have a pH meter, and use grocery store bulk RO water. Fill up my jugs. The TDS reading on the front of the machine generally matches the reading given by my meter. The downside of using store water is that I don't control when, or how the machine is maintained. There are 3 readings on it, 9/2 6 ppm, 11/7 7 ppm, 2/14 14ppm. Those readings seem pretty low, but are obviously going up. When they replace the membrane is completely out of my control.

There have been some horror story threads about machines that aren't being maintained but are being "checked", so having a meter to verify is nice.

LandoLincoln said:

Oh, and the instructions for my Hach Pocket Pro+ pH meter state to rinse off the sensor and cap with deionized water. So deionized water may be useful for a brew day. I've been cheating and just using RO water to rinse it off with.

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DI water is definitely useful to the brewer - just not for brewing. If you do any analysis you use it to:
1)Rinse glassware after washing
2)Make calibration buffers
3)Dilute concentrated samples into range suitable for analysis
4)Do Congress mashes
5)Determine DI mash pH
6)Make up standard solutions
7)Rinse pH electrodes when moving from buffer to buffer, buffer to sample or sample to buffer
8)Clear plugged junction in pH electrode (electrodes that allow this)
9)Quantitatively transfer from measurement vessel (volumetric flask) to boiling flask (ABV determination procedure)
10)Make up to specified volume (distillate or residue in ABV/TE procedures).
11)Mix with standard acids/bases when doing malt titrations

ajdelange said:

DI water is definitely useful to the brewer - just not for brewing. If you do any analysis you use it to:
1)Rinse glassware after washing
2)Make calibration buffers
3)Dilute concentrated samples into range suitable for analysis
4)Do Congress mashes
5)Determine DI mash pH
6)Make up standard solutions
7)Rinse pH electrodes when moving from buffer to buffer, buffer to sample or sample to buffer
8)Clear plugged junction in pH electrode (electrodes that allow this)
9)Quantitatively transfer from measurement vessel (volumetric flask) to boiling flask (ABV determination procedure)
10)Make up to specified volume (distillate or residue in ABV/TE procedures).
11)Mix with standard acids/bases when doing malt titrations

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I had no idea it was used for so much. Maybe it WOULD be a good idea to get a DI filter and hook it up to some bypass valves so one could get some DI water for various purposes on occasion.

That's exactly how I am plumbed. One can buy the exchange cartridges from Cole Palmer (and other suppliers) or one can buy a pure water system that accepts either RO or tap water input (the tap water ones contain an RO cartridge in addition to the ion exchange cartridges). These latter try to trap CO2, kill bacteria, filter residual organics etc. in addition to removing mineral ions missed by the RO system and produce water of 18 M&#937;-cm.

ajdelange said:

DI water is definitely useful to the brewer - just not for brewing. If you do any analysis you use it to:
1)Rinse glassware after washing
2)Make calibration buffers
3)Dilute concentrated samples into range suitable for analysis
4)Do Congress mashes
5)Determine DI mash pH
6)Make up standard solutions
7)Rinse pH electrodes when moving from buffer to buffer, buffer to sample or sample to buffer
8)Clear plugged junction in pH electrode (electrodes that allow this)
9)Quantitatively transfer from measurement vessel (volumetric flask) to boiling flask (ABV determination procedure)
10)Make up to specified volume (distillate or residue in ABV/TE procedures).
11)Mix with standard acids/bases when doing malt titrations

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While all of those uses are valid, the need for hundreds or thousands of gallons of DI water is probably not. For that occasional need for DI, I suggest that a trip to the grocery store will suffice. After 2 years, I'm finally using up my 2 gallons of grocery store distilled water and need a replacement.

I do use RO water for items 1 and 7 above. The rest of the uses are not likely for the typical homebrewer. Again, I point out that DI is NOT necessary for the homebrewer.

Sorry to hijack and bring it back up but, I have an RODI filter because I also have a saltwater aquarium. My setup is after it goes through the the RODI filter it goes to a 30g brute trash can, I'm assuming this isn't food grade so I'll probably run a T at the end of the filter and get a food grade storage for brewing. To where I can fill up both at once. My big question is, is it Fine to just use RODI water for brewing? From what I've read it's fine just checking myself. And I'm safe to assume the RODI water will have nothing in it and I just build it up to where I need it???

RunNakeDnECU said:

Sorry to hijack and bring it back up but, I have an RODI filter because I also have a saltwater aquarium. My setup is after it goes through the the RODI filter it goes to a 30g brute trash can, I'm assuming this isn't food grade so I'll probably run a T at the end of the filter and get a food grade storage for brewing. To where I can fill up both at once. My big question is, is it Fine to just use RODI water for brewing? From what I've read it's fine just checking myself. And I'm safe to assume the RODI water will have nothing in it and I just build it up to where I need it???

Click to expand...

I would tee off after the membrane and use just the RO water for brewing, the DI side for your saltwater setup. All the DI does is get that last little bit of TDS that could cause brown algae or upset a live reef, but for brewing, just use the RO water.

Either is fine for brewing. The extra ppm of this and that which is removed from RO to make DI is probably less that your measurement tolerance in weighing out salt additions so it just doensn't, practically speaking, matter except for item 7 in the list above and perhaps item 1.

There is, however, a cost in running DI. You are depleting your resins and must regenerate them or replace them when they are exhausted. Obviously, if you are running gallons and gallons of brewing water through them you would have to regenerate/replenish more often than if you tap off in front of the exchange bed and just use RO. If the $ + time + PITA factor in regeneration is immaterial to you then it really doesn't matter which you use.

I smoke through DI water when autoclaving stuff. My sterilizer uses a half gallon during a cycle. Anything but DI seems to leave a mineral film inside.

If you boil 1,000,000 cc (1,000 L) of RO water at 1 ppm you will leave 1 gram of stuff behind.

it's a REALLY big autoclave.

I clean my boat in it sometimes

RunNakeDnECU said:

Sorry to hijack and bring it back up but, I have an RODI filter because I also have a saltwater aquarium. My setup is after it goes through the the RODI filter it goes to a 30g brute trash can, I'm assuming this isn't food grade so I'll probably run a T at the end of the filter and get a food grade storage for brewing. To where I can fill up both at once. My big question is, is it Fine to just use RODI water for brewing? From what I've read it's fine just checking myself. And I'm safe to assume the RODI water will have nothing in it and I just build it up to where I need it???

Click to expand...

White, gray, and yellow Rubbermaid Brutes are food-grade HDPE - that's why they are so popular in the marine aquaculture world.

Russ

butterpants said:

it's a REALLY big autoclave.

I clean my boat in it sometimes

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Typically anything under 20 ppm is considered suitable for use as a "spot free" rinse for cars, boats and the like. Meaning that in most instances RO is all that's needed, rather than RODI.

Buckeye_Hydro said:

White, gray, and yellow Rubbermaid Brutes are food-grade HDPE - that's why they are so popular in the marine aquaculture world.

Russ

Click to expand...

Are those the only acceptable colors? I read elsewhere that all were NSF certified and safe for storing water.

Apparently my info was dated. I did a little homework:
Rubbermaid Brute Container
10 Gal. Brute
20 Gal. Brute
32 Gal. Brute
44 Gal. Brute
55 Gal. Brute

Dolly
2640

Lid
10 Gal. Brute Lid
20 Gal. Brute Lid
32 Gal. Brute Lid
44 Gal. Brute Lid
55 Gal. Brute Lid

[20] In Standard 2 these containers are available in: black, blue, brown, burgundy, dark
blue, dark green, dark navy, fuschia, gold, gray, green, light beige, light blue, light
gray, natural, navy, orange, pink, purple, red, silver, teal green, white, or yellow.
Fuschia, navy, and purple are only acceptable for usage with the following food contact
types: alcohol less than 15%, aqueous, bakery products with no free fats or oils on
surface, dairy - oil in water emulsions, and dry solids.
[21] The production date is shown on each model. Models produced after January 1, 1999 are
NSF Certified.
[22] Available in straight wall or vented.


Russ

Thanks for looking into it. My 32G dark green brute was about to be dumped and moved outside.

Not sure on when the change was made. Last time I researched this was a few years ago.