Reverse Osmosis (RO) Water Treatment 101

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

#1: Post by Rod Carmer »

I have read several threads and comments about RO systems. Here is a brief on RO systems. If you have comments or questions I am pleased to answer.

A typical residential RO system consists of the following:

1. Sediment Filter - This reduces the level of turbidity or particulate from the supply water to protect the carbon filter and RO membrane.
2. Carbon Filter - This reduces the chlorine and chloramines to protect the TFC (Thin Film Composite) membrane.
3. TFC Membrane - This reduces the level of TDS (Total Dissolved Solids) from your supply water. Typically when new the membrane will reduce 95-98 % of the TDS in water. Most TFC membranes are rated in GPD (Gallons Per Day). Water Temperature, TDS and pressure has a direct effect on the volume of water that is produced by the system. Most water supplies have 350 -650 ppm (Parts Per Million) TDS. If you remove 95% of the TDS you will have 17.5 ppm. This is not sufficient TDS for optimum extraction of coffee. (Coffee Professionals Can comment on this)
4. Auto Shut Off Valve -This shuts the incoming water off when the tank is full.
5. Storage Tank - This stores the energy produced by the system. Remember that a system rated at 35 GPD will make 35 gallons of water in 24 hours. In one hour it will only make 1.46 gallons of water. Typical storage tanks will hold about 2 gallons of water.
6. Post Carbon - This eliminates any tastes that can develop from sitting stagnant in the storage tank. People say it refreshes the water.
7. Auxiliary Faucet - There are hundreds of standard faucets available and many specialty designer faucets from suppliers across the country. This will help you keep your kitchen decorum consistent.

Most residential RO systems retail from $ 295.00 to $ 1,200.00.

RO systems "DO NOT" add anything back in the water reclamation for municipal water supplies.

In terms of "Wasting Water" there are thousands of scenarios that prove that the amount of water used for RO systems is much less than many common practices.

Scenario: You use 2 gallons of RO water per day. That means you used 10 gallons of water to produce that 2 gallons. 8 gallons of energy was used.

Taking a shower 10 minutes longer than needed wastes approximately 20 gallons of water.
Washing half a load of laundry. Whether at home or a Laundromat wastes 30 gallons of water.
Rinsing the dishes then putting them into a dishwasher wastes 20-30 gallons. Rather than just washing them in a plugged sink.

My goal here is to educate. If you have any questions or concerns for Water Treatment Equipment I would like to answer them to the best of my ability.
Rod Carmer
Cirqua Customized Water

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another_jim
Team HB

#2: Post by another_jim »

One lively question is the efficacy of calcite filters for adding back minerals. The combo of reverse osmosis and calcite is frequently recommended as a scale safe way of getting acceptable espresso water. If the water comes out of the RO system with, say 10ppm to 15ppm TDS, to where will a calcite filter take it?
Jim Schulman

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GC7
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#3: Post by GC7 »

Rod

Most people here looking for espresso options are as you have looking at smaller systems (30 gallon or so). However, we are building a new home where we need to use well water as a supply and a new well should more then supply our needs but the ppm is in the 200-300 range. Clearly a softener will be required. By contrast my current beautiful tap water is about 30 ppm.

Is an entire home RO system a good option if we are talking about 300 gallons per day or so. I'm not a great fan of the salt based softening systems.

Thanks

Rod Carmer

#4: Post by Rod Carmer »

GC7,

I do not suggest a whole house RO system. This is very rare. The cost is astronomical and unnecessary. I would not suggest a system with out a water analysis first. An Ion Exchange system for the purpose of minimizing the hard water deposits would be desirable at a POE (Point of Entry) into the house. Then a POU (Point of Use) water treatment system would be good for the water you consume. Again, I have seen where in large dwellings a Whole House RO system has been put in place but the lines were laid during construction using PEX tubing. These lines were used only for water that would be consumed or for cooking, cleaning food, etc.. There are separate lines for toilets, showers, dish washing, etc... Another note if you have well water with only 10-17 grains hardness. Count your blessings. Where are you located? City State?
Rod Carmer
Cirqua Customized Water

Rod Carmer

#5: Post by Rod Carmer »

Jim,

There are other variables that need to be taken in effect when specifying a Calcite filter to "Add" minerals to RO water or low TDS water. If the Ph level is above 8.5 then the calcite material will not dissolve in water. Many municipal water supplies have this level of Ph and Calcite filters have proved ineffective. Lower Ph will increase the dissolving rate.

Contact time is also important for the proper level of induction of calcite into the process water.

Any company that just suggests a solution without the understanding of specific dynamics of the supply water is just that. Selling product.

Without knowing the specific supply water dynamics we cannot answer that question effectively. Sorry.
Rod Carmer
Cirqua Customized Water

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another_jim
Team HB

#6: Post by another_jim »

Um ... I asked about a calcite filter downstream of an RO system that produces 10 to 20 ppm TDS water. So the alkalinity would be around 5 to 10 mg/L, and the actual pH would be around 6.25 to 6.5. If there are different ways of installing calcite filters, it would be nice to get a primer on this.

Tropical fish owners, who post a lot of technical information about water treatments, usually build there own calcite beds to get the exact alkalinity levels their fish like
Jim Schulman

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GC7
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#7: Post by GC7 »

Rod Carmer wrote:GC7,

I do not suggest a whole RO system. This is very rare. The cost is astronomical and unnecessary. I would not suggest a system with out a water analysis first. An Ion Exchange system for the purpose of minimizing the hard water deposits would be desirable at a POE (Point of Entry) into the house. Then a POU (Point of Use) water treatment system would be good for the water you consume. Again, I have seen where in large dwellings a Whole House RO system has been put in place but the lines were laid during construction using PEX tubing. These lines were used only for water that would be consumed or for cooking, cleaning food, etc.. There are separate lines for toilets, showers, dish washing, etc... Another note if you have well water with only 10-17 grains hardness. Count your blessings. Where are you located? City State?
Thanks for that analysis Rod. It makes a good deal of sense. We are building in upper Westchester County NY (South Salem) adjacent to the CT border. It's right near some of the reservoirs that serve the nice soft water I now consume but the town where our property resides can't use it. The current well needs to be redone along with the whole house. If I Brita filter the current well water it get to about 105 ppm or so TDS. My espresso will either get RO water (most likely) or I will drag containers of real distilled water from my lab and just add back enough hard water for taste but without requiring descaling on any regular basis.

cruzmisl

#8: Post by cruzmisl »

Rod,
I currently have a barrel type softener and a diaphragm tank that supplies about 2.5 gallons of water. I found that the softener and .5 micron filter attached caused some pump cavitation due to the low GPM. Anyway, I bought a TDS meter to determine when to recharge my resins but as it turns out I should have done more reading as they don't work with ion exchange salt softeners :?

My municipal supply coming in has a TDS of about 110-115ppm. I'm not sure what the ideal TDS is for coffee taste and safe operation of the machine. I was considering adding an RO system which will bring thre TDS down to <5ppm and using a "T" and a ball valve to reintroduce tap water until I reach the desired TDS.......what is the desired hardness anyway?

Thanks for any thoughts.
Joe

Javacat

#9: Post by Javacat »

My experience with the calcite filter that Chris' Coffee sells is that it will bring up the level of hardness up to around 25 ppm from the 12-15 ppm of straight RO water, and has very minimal effect on pH. If you do install one of these filter be sure that you have a filter downstream as some of the salts tend to migrate out of the filter and into the machine which can clog a small gicleur if your machine has one.

aab1

#10: Post by aab1 »

I have an RO-DI system I got on ebay years ago for about $100 that produces water that's 0 to 1 ppm tds (it came with a digital tds meter).

In my water cooler bottle I always add Himalayan salt to bring it back up to 125-150 ppm but I never bother doing this in my espresso machine as I'm skeptical of the taste difference, then again the taste difference of plain water between 0 and 125 ppm is more than noticeable, I just have a hard time imagining it would be noticeable in espresso/coffee. I'll actually try a comparison now.

Those filters that do add back minerals, to how much would they increase 0-1 ppm water? And how long does the remineralization cartridge last?

Thanks

***UPDATE***

Well I did the test, long story but I couldn't use my insulated glasses I just posted in another thread so the first espresso with 0-1ppm water got fairly cool by the time I added salt to the water tank and mixed it, then flushed the machine's internal water. I got the ppm a bit higher than expected (I'm used to adding the salt to 5 gallon bottles, not 1/2 gallon water tanks), it measured at 269 ppm.

The only difference I seemed to noticed was that the espresso seems a bit less bitter, is this the kind of difference I should expect between 0ppm water and 269ppm water?

In any case I may start adding salt on each refill. I actually dilute Himalayan salt rocks into a glass jar with pure water and I need 1 tablespoon of that to bring 5 gallons of water from 0 to 150 ppm. What I can do is use an eyedrop bottle and put the salt solution in there and simply figure out how many drops I need to add, it would be about 20 drops to bring the machine's water tank to around 250 ppm.

Would doing this cause scale buildup? I've always used pure water before and after years of daily use never had any scale problem (my older Keurig machine had a built in actual scale sensor [not just a timer like espresso machines] and it never turned on, but it was always 0-1ppm water going through it so scale couldn't form).