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Author Topic: TDS blending valve to mix RO and tap water  (Read 3260 times)

Offline hydrocynus

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TDS blending valve to mix RO and tap water
« on: January 03, 2021, 07:32:33 am »
Hello all, I am looking for an inexpensive solution to blend to my liking RO water (already have the equipment) with my pre-RO water to add back minerals to the RO water. My TDS pre RO treatment is indeed 450ppm which gives a bitter taste, but has good minerals. So, I want to lower it to about 120ppm. The pH is slightly blow 7 for the RO and the pre-RO is 7.8, so I should end with decent pH after the blending. Thanks!!!

Online goose

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Re: TDS blending valve to mix RO and tap water
« Reply #1 on: January 03, 2021, 08:36:55 am »
Why don't you try 1 part of your pre-RO water and three parts of RO as a start.  That should get the TDS down to close to your desired range and adjust your dilution rate if necessary to dial it in. You can always then add additional minerals to get you percentages back to what you want for your water profile.

You also might consider downloading Bru'n Water from Martin's website.  You will get a free stripped down version that will work and if you send him something like a $5.00 donation, you will get the full blown version.  There is a dilution scheme in it where you can enter your pre-RO water and dilute it to what you want for mineral concentration.

FYI, my well water is really crappy here so I use only RO water and build my profiles from there.  I used to get water from a local spring and dilute it with RO.  The problem is that there was so much carbonate in it that I could only use it for dark beers.  The hardness always made my light beers taste like drinking a stone and the profile was just off enough that the darker beers suffered as well, even after diluting.  RO is cheap, even cheaper if you have a home system.  I don't like to tax my RO system since we use it for drinking water and cooking but have used it in when I need to brew on a day when the water store is not open (i.e. I forgot to go buy some).  I can get 5 gals. of RO from the local water softener store (Culligan or Clearwater) for $1.50.  It's convenient as the closest one is only about 2 miles away.
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Offline hydrocynus

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Re: TDS blending valve to mix RO and tap water
« Reply #2 on: January 03, 2021, 09:58:56 am »
Thanks for your answer. I have decided not to get a whole house RO system because of the costs and also because of the large amounts of wastewater created. Plus, my well water tests placed me just under the limit for RO (sulfides at 3.7ppm, TDS at 450ppm, no iron). So I have an air drawn system to get rid of the sulfides and a calgon activated carbon with KDF 85 for the filtration and a softener with brine tank for the elimination of the hardwater. All works well but of course the TDS remain constant and give a bad taste for my water.

The under the sink filtration is currently a double Frizzlife MK99/MP99. What I need is constant good water using a blend of RO water and my filtrate for drinking water and occasional brewing.

I have found blending valves but they are mechanical and would maybe work with an atmospheric storage tank but not well with a bladder tank. Still looking at options.

Again thank you

Offline Bob357

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Re: TDS blending valve to mix RO and tap water
« Reply #3 on: January 03, 2021, 10:36:54 am »
Hello all, I am looking for an inexpensive solution to blend to my liking RO water (already have the equipment) with my pre-RO water to add back minerals to the RO water. My TDS pre RO treatment is indeed 450ppm which gives a bitter taste, but has good minerals. So, I want to lower it to about 120ppm. The pH is slightly blow 7 for the RO and the pre-RO is 7.8, so I should end with decent pH after the blending. Thanks!!!

A couple of things to note:

1. TDS doesn't speak to the levels of individual minerals, and an RO system doesn't reduce individual minerals by the same percentages.

2. Water pH has little influence on mash pH. Alkalinity does.

Without analysis of your source water and RO water, you're guessing at what the outcome of blending the two will be, and assuming it will solve your bitter taste problem. If you're looking at 75% RO anyway, for the extra $ or less/batch, why not just go with pure RO and add Gypsum and/or Calcium Chloride as needed? They're cheap, literally, pennies per batch and you'll know what's in your brewing water. Either way, you may need to deal with mash pH as well.
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Offline mabrungard

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Re: TDS blending valve to mix RO and tap water
« Reply #4 on: January 03, 2021, 12:47:41 pm »
Blending valves are difficult to get set properly and they can’t be relied on to provide a constant water quality. I can’t recommend that approach. Running off calculated volumes of RO and tap water is more likely to produce a reliable result.
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Offline hydrocynus

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Re: TDS blending valve to mix RO and tap water
« Reply #5 on: January 03, 2021, 06:56:07 pm »
Thanks for your answers. Adding minerals to RO water is an option but not as good as blending with the minerals already in the filtrate. It is like modern agriculture with the macro nutrients present but lacking the micronutrients. I might work on a solenoid valve controlled by an Arduino...

Offline spurviance

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Re: TDS blending valve to mix RO and tap water
« Reply #6 on: January 04, 2021, 08:17:52 am »
What you're proposing to do is exactly what I do.  I send a sample of my well water to Ward Labs every year or so to get latest mineral content.  Then blend it with RO water to get the profile I'm looking for as per the water profile spreadsheet I use.  I can make tweaks as desired using gypsum, CaCl etc...
We have a RO filter under our kitchen sink that has a 2 gal reservoir, but my wife gets mad when I use that as it takes a while to refill, so lately I've been paying $2 at a local grocery store to fill up a 5 gal jug with RO water.  Works for me.
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Offline hydrocynus

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Re: TDS blending valve to mix RO and tap water
« Reply #7 on: January 04, 2021, 10:42:01 am »
Maybe I should have written this. I am an oceanologist and limnologist Ph.D./University Prof. and I have my own water quality lab so I know exactly what what well water analyses are, what my flitrate is and thus how I need to blend. My original question was is there a TDS blending solenoid computer controlled valve that is available commercially so that I do not need to program my own with an Arduino?
Thanks


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Re: TDS blending valve to mix RO and tap water
« Reply #8 on: January 04, 2021, 10:53:19 am »
Maybe I should have written this. I am an oceanologist and limnologist Ph.D./University Prof. and I have my own water quality lab so I know exactly what what well water analyses are, what my flitrate is and thus how I need to blend. My original question was is there a TDS blending solenoid computer controlled valve that is available commercially so that I do not need to program my own with an Arduino?
Thanks

The question remains, if you want 80/20 RO and tap water, why not fill 80% of the volume from RO and then 20% from the tap?  Even if you want to automate this, a blending valve wouldn’t solve the problem of needing a flow meter to measure precise volumes.

Offline hydrocynus

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Re: TDS blending valve to mix RO and tap water
« Reply #9 on: January 04, 2021, 10:59:03 am »
Yes, I could do this in a container but what I am looking is a permanent solution that will provide me with blended water right out of the faucet.
« Last Edit: January 04, 2021, 11:35:43 am by hydrocynus »

Offline rburrelli

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Re: TDS blending valve to mix RO and tap water
« Reply #10 on: January 04, 2021, 03:46:34 pm »
Yes, I could do this in a container but what I am looking is a permanent solution that will provide me with blended water right out of the faucet.
So you never mention brewing as a part of this. You want ALL of your water to be treated. Is that the purpose of your post?
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Offline Saccharomyces

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Re: TDS blending valve to mix RO and tap water
« Reply #11 on: January 09, 2021, 10:21:38 am »
My TDS pre RO treatment is indeed 450ppm

I cannot imagine having to deal with water with a TDS of 450ppm. I have never had to deal with water with a TDS above 145ppm or so and that was well water after being neutralized with a calcite filter.  I just checked my unfiltered chlorinated tap water and it measured 78ppm TDS.  I need to get a new pH meter to replace the Milwaukee MW101 that I sold during my hiatus to measure the pH.


Offline chinaski

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Re: TDS blending valve to mix RO and tap water
« Reply #12 on: January 09, 2021, 02:32:50 pm »
Yes, I could do this in a container but what I am looking is a permanent solution that will provide me with blended water right out of the faucet.
Could you plumb a mixing faucet (think kitchen faucet) with tap and the RO instead of the hot water line; somehow figure out when you've got it mixing in the right proportions and then remove the handle to keep it there?

Offline smkranz

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Re: TDS blending valve to mix RO and tap water
« Reply #13 on: January 12, 2021, 08:40:25 pm »
My TDS pre RO treatment is indeed 450ppm

I cannot imagine having to deal with water with a TDS of 450ppm. I have never had to deal with water with a TDS above 145ppm or so and that was well water after being neutralized with a calcite filter.  I just checked my unfiltered chlorinated tap water and it measured 78ppm TDS.  I need to get a new pH meter to replace the Milwaukee MW101 that I sold during my hiatus to measure the pH.
Mark, the tap water out here in the country is crazy high.  Assuming the digital TDS meter that I use with my portable RO filter is accurate, it typically reads ~350.  Depending on the beer, I usually use a 25-33% charcoal filtered tap to RO ratio.  It would certainly be handy to also have an RO faucet at the sink, but for general drinking and cooking water we mostly just use charcoal filtered tap water. 

Other than for brewing, we only use the RO water to fill the coffee maker, and aquarium replenishment, from jugs.  The waste water from the RO filter gets recycled either into the yard, or captured to water potted plants...whether they like it or not.


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Offline Saccharomyces

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Re: TDS blending valve to mix RO and tap water
« Reply #14 on: January 15, 2021, 02:30:54 pm »
Mark, the tap water out here in the country is crazy high.  Assuming the digital TDS meter that I use with my portable RO filter is accurate, it typically reads ~350.  Depending on the beer, I usually use a 25-33% charcoal filtered tap to RO ratio.  It would certainly be handy to also have an RO faucet at the sink, but for general drinking and cooking water we mostly just use charcoal filtered tap water. 

That is because you are in the part of the county that is on top of a dolomite formation, so you have lots of calcium and magnesium carbonate hardness.   In the southern part of the county where I used to live, the rock formation had zero limestone and no dolomite.  The water came out of the ground with a TDS in the 70ppm range and pH below 6.   I had to install a calcite filter to save my plumbing fixtures.