Reverse Osmosis vs Distilled Water

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Acavia

#1: Post by Acavia »

For my coffee water, I buy distilled water, and add minerals back.

I am considering a reverse osmosis set-up. Is it ~0 TDS water as distilled is? Would it be a 1 for 1, same recipe and same result using reverse osmosis water instead of distilled?

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homeburrero
Team HB

#2: Post by homeburrero »

It depends mostly on the feed water purity and some on the efficiency of the RO system. With good water pressure and a good membrane most run in the 97% reject rate ballpark, so for 200 ppm feed water you might get 6 ppm RO if the system is working well. Not 0 ppm but in most cases is low enough that you can use it in a recipe the same as you would use distilled or de-ionized.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Acavia (original poster)

#3: Post by Acavia (original poster) replying to homeburrero »

Is deionized 0tds?

Any practical systems for home-use you would recommend? And estimated costs?

Acavia (original poster)

#4: Post by Acavia (original poster) »

homeburrero wrote:It depends mostly on the feed water purity and some on the efficiency of the RO system. With good water pressure and a good membrane most run in the 97% reject rate ballpark, so for 200 ppm feed water you might get 6 ppm RO if the system is working well. Not 0 ppm but in most cases is low enough that you can use it in a recipe the same as you would use distilled or de-ionized.
Also, if the source water is well water AFTER a water softener, will it take out the sodium etc., from the softener, and be closer to 0 than if the hard well water went through the RO system?

Nunas
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#5: Post by Nunas replying to Acavia »

I've found this to be true, but the difference is not striking. What I have noticed when we put a water softener between our very hard city (well) water (~400+ ppm) is that the RO system filters and membrane last for a very long time. By a long time, I mean years, not months between filter changes. We use a lot of RO water, at least several litres per day, and when we're wine making we use several gallons a day (often running the accumulators dry). Before the water softener, filters lasted three or four months at most. Our last change post-softener filter change was over three years ago and there's no sign of deterioration.

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homeburrero
Team HB

#6: Post by homeburrero »

Acavia wrote:Also, if the source water is well water AFTER a water softener, will it take out the sodium etc., from the softener, and be closer to 0 than if the hard well water went through the RO system?
It will remove the sodium added by the softener, but won't get it much closer to zero than it would be if it were unsoftened. Softening is a good idea and is often necessary to avoid fouling the RO membrane. When shopping for RO systems you need to make sure your feed water is below the max hardness and also below the max TDS in the system spec..

Edit addition:
I posted the above before seeing that Nunas had already answered it nicely. Good to see that we agree here. Also noted that I failed to answer the OP question about de-ionized water being 0 ppm. It generally is close to that, usually less than a few ppm. I get de-ionized at my grocery store refill station, which is local tap RO that is further purified by a mixed bed ion exchange resin. It reliably gives me readings of 0 - 1 ppm. A Zerowater pitcher is a de-ionizer with a mixed bed ion exchange resin and produces a near zero ppm water. Those come with an inexensive TDS meter that you use to monitor that your exchange resin is not depleted, and you are advised to change the filter if the reading goes up to 6 ppm.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Deephaven

#7: Post by Deephaven »

Post softener mine pulls the water down to 4-5. I would NEVER run mine without being pre-softened as my well hardness is well off the charts in the wrong way. Filters last longer post softening and iron filter.

Make sure to add a calcite filter after for remineralization and enjoy.

**Edit: left out the without implying the wrong message

zero610

#8: Post by zero610 »

Are RO and distilled water basically interchangeable when mixing your own water (with something like Third Wave or concentrate mixes)? Does less than 10ppm TDS post RO make any sort of detectable difference in the end product?

Deephaven

#9: Post by Deephaven »

Fundamentally I would treat them the same. 10ppm is really somewhat inconsequential. You could surely measure what it is and compensate but I wouldn't go that far.