Is RODI water safe to drink?

[Randy Holmes-Farley Verified Community Expert]

For sure, DI water tastes bad. Does it still taste bad when made into coffee? Don't know. I don't like the taste of black coffee in any water.

Now coffee ice cream, that's another story.

 

[Pod_01]

For sure, DI water tastes bad. Does it still taste bad when made into coffee? Don't know. I don't like the taste of black coffee in any water.

Now coffee ice cream, that's another story.

Hmmmmm….. espresso time…

 

[megator84]

Sorry folks, but drinking deionized water in and of itself will not hurt you in the slightest. The idea behind this is an inappropriate extrapolation from laboratory science. Extremely pure water has a large capacity to dissolve ions from various containers that it's put into, which is why if one puts 18.3 megaohm laboratory grade water into a glass vessel, the resistivity will quickly drop into the 0.5-1.0 megaohm range. That's partly from the adsorption of CO2 in the air, but also dissolution of sodium and silica from the vessel walls itself. And if you keep highly pure water in a 316 stainless steel system that's not "passivated", you will get corrosion of the steel walls as a very tiny amount of it dissolves into the water (this is called "rouging").

These effects have led some to inappropriately assume that highly purified water is "corrosive" and that it will remove minerals from your body as they dissolve into the water if you drink it. There is a rather serious logical problem with this assertion, which is that your stomach contains a massive amount of electrolytes compared to what is required to make highly pure water into "normal" water. It's true that if you only drank highly purified water and your food was deficient in minerals, then at some point you might develop a mineral deficiency. This is often cited as evidence that drinking highly purified water is "bad for you". What alarmist websites that espouse this dreck aren't telling you is that you would likely develop the same mineral deficiency regardless of whether you were drinking "normal" water or highly purified water. And for the average person in developed countries, the vast majority of your daily mineral intact is from food, not water.

However, there are several reasons not to drink water from your average hobbyist's RODI system, though it has nothing to do with the water that's produced being inherently bad for you. The first is taste - a lot of what we perceive to be "good tasting water" comes from the minerals that are in it. Highly purified water tends to taste "flat". This is why, btw, that bottled water companies use RODI systems to purify the municipal sources of water that they use, then add sodium, calcium and magnesium salts back into it before they bottle it. The second reason not to drink hobbyist-produced RODI water has to do with sterility. Municipal sources add chlorine/chloramine to water for a reason, and that's to prevent you from getting a bunch of live pseudomonas and escherichia (among other genuses) when you get a drink of water from the sink. In a hobbyist's RODI system, the carbon blocks remove the chlorine/chloramine, so the rest of the system downstream from the pretreatment stage can definitely grow several types of problematic bacteria that you wouldn't want to drink.

That's why RODI systems that are used for manufacturing beverage products have 2 additional controls in the system, which are UV sterilization and ultrafiltration. These systems are also regularly sterilized with peroxide-based sterilants to prevent the growth of biofilms.

Bottom line - if you want to use RODI in an application were it will be heated/boiled, there's no reason not to. But don't drink it straight from your RODI system without adding in some additional components to ensure its microbiological safety.

Can you use it in a humidifier?

 

[Perthegallon]

Can you use it in a humidifier?

It would be better since it doesn't crude the lines

 

[Randy Holmes-Farley Verified Community Expert]

Can you use it in a humidifier?

In an evaporative type it's a great choice. In an ultrasonic type, there's a very small risk of bacteria in the droplets that you might inhale.

 

[Malcontent]

RO water is great for humidifiers especially ultrasonics. In the winter I actually use more RO water for humidifiers than my tanks.

I also melt the rime I scrape out of my chest freezers (in lieu of defrosting them) and use it in humidifiers.

 

[Sophie"s mom]

Would it be unhealthy because it's filtered too much?

Last question...can you use this in an iron since all the metals are filtered out.

I wanna make coffee with it or use in baby bottles.

You can drink RO water, but as others have said, you CAN NOT drink RODI. The deionization process makes it bad for us.

 

[Randy Holmes-Farley Verified Community Expert]

You can drink RO water, but as others have said, you CAN NOT drink RODI. The deionization process makes it bad for us.

That is not true, and is not what I said earlier in this thread.

RO water can readily have bacteria growing downstream of the membrane, and sanitization of that water somehow before drinking is important. Either a UV on the output, or careful sanitization of the system periodically. The DI does not impact that concern.

OTOH, lack of minerals in some water you drink is not a big deal. It tastes bad, but is not a health risk. You get plenty of minerals in other ways, and if it were important, people would be in serious trouble as the minerals actually in tap water vary greatly from place to place.

Assessment of the extent of bacterial growth in reverse osmosis system for improving drinking water quality - PubMed

This study was carried out to assess reverse osmosis (RO) treatment efficacy of drinking water in terms of biological stability in the distribution system. Two flat-sheet RO membranes were used in this study. Experiments were designed to investigate the growth of biofilm and bulk phase bacteria...

pubmed.ncbi.nlm.nih.gov

"In spite of the low nutrient contents and few cells in the RO permeates, monitoring of the model distribution systems receiving the RO permeates showed that remarkable biofilm accumulation and bulk cell growth occurred in the RO permeate water. "

"Therefore, efforts to minimize bacterial growth in the RO permeate water and in the distribution system must consider post-disinfection."

 

[Sophie"s mom]

That is not true, and is not what I said earlier in this thread.

RO water can readily have bacteria growing downstream of the membrane, and sanitization of that water somehow before drinking is important. Either a UV on the output, or careful sanitization of the system periodically. The DI does not impact that concern.

OTOH, lack of minerals in some water you drink is not a big deal. It tastes bad, but is not a health risk. You get plenty of minerals in other ways, and if it were important, people would be in serious trouble as the minerals actually in tap water vary greatly from place to place.

Assessment of the extent of bacterial growth in reverse osmosis system for improving drinking water quality - PubMed

This study was carried out to assess reverse osmosis (RO) treatment efficacy of drinking water in terms of biological stability in the distribution system. Two flat-sheet RO membranes were used in this study. Experiments were designed to investigate the growth of biofilm and bulk phase bacteria...

pubmed.ncbi.nlm.nih.gov

"In spite of the low nutrient contents and few cells in the RO permeates, monitoring of the model distribution systems receiving the RO permeates showed that remarkable biofilm accumulation and bulk cell growth occurred in the RO permeate water. "

"Therefore, efforts to minimize bacterial growth in the RO permeate water and in the distribution system must consider post-disinfection."

Wow! Thank you for that. More info on thIs subject than I have ever seen ANYWHERE.

 

[Quietman]

I have very hard water and while RO is a fine option for a humidifier, I use an anti-scaling product for my humidifier. A cap full every 3-4 fill ups does the trick and the bottle lasts for a season or more. Plus it has antibacterial in it as well (designed for humidifiers I). I haven't run the numbers but I go through DI media (anion) pretty quick anyway so it has to be more economical then running 3 gallons a day for my humidifier use. So for my usage, DI is not best option for humidifier, although it's a functional option.

I do use RO (tap off before DI) for my wife's plants and my freshwater fish and I can see that being more economical and probably still has 99% of the benefits if not exactly convenient with my bucket fill setup.

 

[Hans-Werner]

RO water can readily have bacteria growing downstream of the membrane, and sanitization of that water somehow before drinking is important. Either a UV on the output, or careful sanitization of the system periodically. The DI does not impact that concern.

Many folks use RODI water for preparing tea or coffee. I guess boiling of the water is an adequate sanitization against bacteria.

 

[Randy Holmes-Farley Verified Community Expert]

Many folks use RODI water for preparing tea or coffee. I guess boiling of the water is an adequate sanitization against bacteria.

Yes, and/or they like living dangerously. lol

 

[Hans-Werner]

Yes, and/or they like living dangerously. lol

I am a survivor! I have survived using RO water for preparing tea. Now I live in a place with tap water less than half as hard as where I lived doing this.

 

[gbroadbridge]

I am a survivor! I have survived using RO water for preparing tea. Now I live in a place with tap water less than half as hard as where I lived doing this.

If you go to a grocery store or gas station in many Asian countries, the bottled drinking water on the shelf is often RODI water.

While travelling, I've drunk thousands of gallons of it as the tap water is unsafe to drink.
Everyone, even locals, drink it and have it delivered in 10 gallon water cooler containers.

 

[Pod_01]

Yes, and/or they like living dangerously. lol

Randy is the RODI water or bacteria in the RO water that you think is dangerous?

Many coffee shops use RO systems with remineralization and likely UV. To get the best flavour etc…

For home use you can buy mini 3 part dosing system:

To get the Alk, Calc and Mag back in.

I always wondered if bacteria can grow after UV just as much as after RO membrane so boiling the water seems like a reasonable step.

 

[Minifoot77]

As a US marine in the water purification M.O.S. (1171) we us a rowpu or reverse osmosis water purification unit and most of the water marines are given on deployment is ro water...