[tomsawyer]

Good RO is probably only 10-20ppm of salt vs <1ppm for distilled.  I don't think either one will kill yeast in under 15min.  Most water is lower than the osmotic concentration inside the cell, thats why its beneficial to rehydrate yeast prior to pitching into a high osmotic strength wort.

Yes, they make wort the same as we do, and the mash has the same mineral requirements.

[morticaixavier]

[...]2- sure you can do a 2.5 gallon boil and then top off with filtered or boiled and cooled water I would not use distilled water though as the mineral content in spring water is beneficial to the flavor and the yeast health. Just a FYI don't ever use reverse osmosis water though as it can kill the yeast as the osmotic pressure of RO water is higher than the cell wall of the yeast.

[...]

Are you sure about this? RO water is simply water that has been purified by being forced through a semi permeable barrier. Distilled water has less minerals than RO as it was evaporated and recondensed.

You're not supposed to use RO/distilled water for dry yeast rehydration. I think that's what he was referring to.

As far as wort production from extract, I would recommend RO/distilled since the extract was already made with plenty of minerals in the water.

Ahh yes. I have heard that you should not use RO or distilled for rehydration. However, I would think the osmotic pressure of RO water is, if anything, slightly lower than that of spring of tap. But only very slightly as there are less dissolved solids in the RO than the spring.

[aschecte]

[...]2- sure you can do a 2.5 gallon boil and then top off with filtered or boiled and cooled water I would not use distilled water though as the mineral content in spring water is beneficial to the flavor and the yeast health. Just a FYI don't ever use reverse osmosis water though as it can kill the yeast as the osmotic pressure of RO water is higher than the cell wall of the yeast.

[...]

Are you sure about this? RO water is simply water that has been purified by being forced through a semi permeable barrier. Distilled water has less minerals than RO as it was evaporated and recondensed.

Regardless in an extract batch all those minerals are already in the extract and there is no need for more.

Yes I'm sure about the RO water we learned that in school as I went to school for brewing..... it is moreso for yeast starters or even in high amounts in fermentation. What will happen to RO water when all and I mean all of the minerals, toxins, VOC, etc are pulled through a thin film cellulose it actually changes the composition of the water and creates what is called osmotic pressure. There have been numerous brewing case studies as well as microbiology studies showing the impact of the Osmotic pressure of H2o on cell walls causing them to implode not explode but implode as the pressure of the water has increased to a level higher than a cell can tolerate. Now distilled water is fine except for the fact that any of the waters character has been removed I love distilled water when I build a profile to a specific region. for extract though you  are correct all the monerals and nutrient are already present in the LME or DME.

[flbrewer]

So filtered tap water for the partial?

[aschecte]

So filtered tap water for the partial?

yes that would be fine though I would either boil it first to get rid of chlorine or use either potassium or sodium metabisufate if your water is treated with chloramines.

[flbrewer]

Our filtered water has no chlorine. At least that's what the water softener/ filter installer told us (after the system was installed of course). So I don't care either way, only talking 2.5 gallons. Just want to not screw up this simple step.

[morticaixavier]

[...]2- sure you can do a 2.5 gallon boil and then top off with filtered or boiled and cooled water I would not use distilled water though as the mineral content in spring water is beneficial to the flavor and the yeast health. Just a FYI don't ever use reverse osmosis water though as it can kill the yeast as the osmotic pressure of RO water is higher than the cell wall of the yeast.

[...]

Are you sure about this? RO water is simply water that has been purified by being forced through a semi permeable barrier. Distilled water has less minerals than RO as it was evaporated and recondensed.

Regardless in an extract batch all those minerals are already in the extract and there is no need for more.

Yes I'm sure about the RO water we learned that in school as I went to school for brewing..... it is moreso for yeast starters or even in high amounts in fermentation. What will happen to RO water when all and I mean all of the minerals, toxins, VOC, etc are pulled through a thin film cellulose it actually changes the composition of the water and creates what is called osmotic pressure. There have been numerous brewing case studies as well as microbiology studies showing the impact of the Osmotic pressure of H2o on cell walls causing them to implode not explode but implode as the pressure of the water has increased to a level higher than a cell can tolerate. Now distilled water is fine except for the fact that any of the waters character has been removed I love distilled water when I build a profile to a specific region. for extract though you  are correct all the monerals and nutrient are already present in the LME or DME.

Not trying to be nit picky but you have it a little mixed up.

http://en.wikipedia.org/wiki/Reverse_osmosis The solvent (water) is passed through the membrane, the solute (minerals, etc.) stay on the input side and are flushed away.

Perhaps some of the water scientist can clarify this a bit for us but my understanding is that the less 'stuff' in the water the lower the osmotic pressure on the cell would be thus too many minerals would leave the cell wall. I can see how that would be problem in a starter or rehydration solution.

My confusion with your argument is coming from the fact that you are saying that distilled is fine. RO water is far closer in chemical makeup to tap water than distilled is to tap water. Why would moving from a to b on a continuum be worse than moving from a all the way to c?

[Jimmy K]

There have been numerous brewing case studies as well as microbiology studies showing the impact of the Osmotic pressure of H2o on cell walls causing them to implode not explode but implode as the pressure of the water has increased to a level higher than a cell can tolerate. Now distilled water is fine except for the fact that any of the waters character has been removed I love distilled water when I build a profile to a specific region. for extract though you  are correct all the monerals and nutrient are already present in the LME or DME.

Maybe you could link to one of those studies, because otherwise I'm not following the logic.

[aschecte]

[...]2- sure you can do a 2.5 gallon boil and then top off with filtered or boiled and cooled water I would not use distilled water though as the mineral content in spring water is beneficial to the flavor and the yeast health. Just a FYI don't ever use reverse osmosis water though as it can kill the yeast as the osmotic pressure of RO water is higher than the cell wall of the yeast.

[...]

Are you sure about this? RO water is simply water that has been purified by being forced through a semi permeable barrier. Distilled water has less minerals than RO as it was evaporated and recondensed.

Regardless in an extract batch all those minerals are already in the extract and there is no need for more.

Yes I'm sure about the RO water we learned that in school as I went to school for brewing..... it is moreso for yeast starters or even in high amounts in fermentation. What will happen to RO water when all and I mean all of the minerals, toxins, VOC, etc are pulled through a thin film cellulose it actually changes the composition of the water and creates what is called osmotic pressure. There have been numerous brewing case studies as well as microbiology studies showing the impact of the Osmotic pressure of H2o on cell walls causing them to implode not explode but implode as the pressure of the water has increased to a level higher than a cell can tolerate. Now distilled water is fine except for the fact that any of the waters character has been removed I love distilled water when I build a profile to a specific region. for extract though you  are correct all the monerals and nutrient are already present in the LME or DME.

Not trying to be nit picky but you have it a little mixed up.

http://en.wikipedia.org/wiki/Reverse_osmosis The solvent (water) is passed through the membrane, the solute (minerals, etc.) stay on the input side and are flushed away.

Perhaps some of the water scientist can clarify this a bit for us but my understanding is that the less 'stuff' in the water the lower the osmotic pressure on the cell would be thus too many minerals would leave the cell wall. I can see how that would be problem in a starter or rehydration solution.

My confusion with your argument is coming from the fact that you are saying that distilled is fine. RO water is far closer in chemical makeup to tap water than distilled is to tap water. Why would moving from a to b on a continuum be worse than moving from a all the way to c?

You are correct I have not worded it correctly but my principle remains the same..... you have 2 types of membranes with a RO system and you are correct the water is pulled through the membrance and contaminants stay on the opposite side. you are also correct and I said it backwards the osmotic pressure is lower with RO water with is why it effects the yeast wall membrane.  Where you misunderstand me or did read close enough ( not trying to sound mean ) is I never said distilled water is Ok. I said I like distilled water to adjust a water profile in other words either add gypsum, chalk, Epsom salts etc and build a water profile with it or to dilute a existing profile to hit a target. also we are looking at two completely different scenarios. The first being a all grain brewer I would never in a million years tell a all grain brewer to use distilled water alone and do a mash as the grain itslf does not have the mineral content etc....  for proper fermentation or flavor for that matter. Secondly though we area talking to the OP who has got his first kit and it is a extract batch.... extract has all the nutrient and additional minerals etc... from the actual process of mashing than either condensing or dehydrating the LME or DME that is needed for proper fermentation. heck you don't even need any type of yeast nutrient with extract where with All grain I would strongly recommend it. I am not a water expert and to be honest when I went to school it was many many years ago so I know my knowledge is correct to what we were taught but I may be wording it a bit weird as this is not a topic I discuss on a daily basis.

[morticaixavier]

gotcha,

sounds like we are on the same page now.

bottom line, filtered tap, bottled spring (as long as they are not too mineral), RO or distilled for a first extract batch is just fine.

[tomsawyer]

After six posts and/or the immediate question is answered, the topic is allowed to drift off into the arcane.

If you don't let the yeast sit in RO or distilled too long (<15min) they won't burst.  The salt concentration in the cells pulls water across the cell membrane to rehydrate the yeast.  It doesn't happen in an instant.  Tap water with some salts is safer since the gradient is not as great, but the chlorine issue competes with the lesser osmotic gradient.  It'll all be OK though.

There for a minute I thought you were saying that RO treatment changes water in a way other than simply removing salts/organics.  This is the kind of voodoo that is sold by some in the water treatment business. 

[tschmidlin]

Osmotic pressure only exists across a semi-permeable membrane, so RO water does not have more osmotic pressure than any other water.  It is water.  Osmotic pressure is better understood as the tendency of water to move across the membrane in order to balance both sides.  When there is something that can NOT move through on only one side of the membrane and not on the other it creates physical water pressure on the membrane from things like water that CAN move across the membrane - water will do so until the pressure on both sides of the membrane is in equilibrium.  In reverse osmosis, pressure is added to one side to force the water across the semi-permeable membrane, leaving the other stuff behind.  I'm sure you can google much better explanations.

Yeast in RO water experience higher osmotic pressure than non-RO water, but not higher than distilled water.  Adding extract to the water before adding yeast will relieve the osmotic pressure.

And while there is some osmotic pressure created by using distilled water, it is the best media for long term storage of yeast.

Started this post before all of these other replies.  Bah.

[morticaixavier]

Thanks Toms. Much more clearly stated than I seemed able.

[aschecte]

After six posts and/or the immediate question is answered, the topic is allowed to drift off into the arcane.

If you don't let the yeast sit in RO or distilled too long (<15min) they won't burst.  The salt concentration in the cells pulls water across the cell membrane to rehydrate the yeast.  It doesn't happen in an instant.  Tap water with some salts is safer since the gradient is not as great, but the chlorine issue competes with the lesser osmotic gradient.  It'll all be OK though.

There for a minute I thought you were saying that RO treatment changes water in a way other than simply removing salts/organics.  This is the kind of voodoo that is sold by some in the water treatment business.

HAHAHA no I wasn't saying that it did anything more than pull impurities out of the water.... I'm not a water treatment guy so that was not my intention to mislead anyone, for that matter I think you explained what I was getting at in a few sentences than I could do in multiple posts. bottom line distilled AND RO water is ok but Iwould not rehydrate in it for one and I would strongly recommend building a profile and add salts and other minerals back into it if you choose to use distilled or RO water. as to links that another user asked me to post.... these are all in books published by UCD, Papazian, Palmer where they discuss water profiles , things to avoid and ways to fix water problems and make better brewing water.

[tomsawyer]

If you really want to be nice to your yeast, rehydrate with a product called GoFerm.  Its a nutrient solution that provides a nice boost during rehydration.  I use it for my wine yeasts, never tried it for brewing.  Then again I mostly use liquid yeasts and starters for those.