Confusing field of kitchen water purification

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Rmk9785e

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The experts may know it all but for the commoner, the discussions and options are baffling without some clear answers. If would be nice if the collective wisdom here would narrow it down to the top 5-10 configurations and the topic is stickied for all new inquiries but clear choices are hard to find even after going through lengthy threads.
I find an opinion: "Whatever system brand you choose, make sure it uses a standard Dow style membrane and standard 2x10 prefilter housings. DO NOT purchase a system with proprietary cartridges." Which makes sense but how does one know that any given system uses Dow style membrane and where does one find the pre-filter housing sizes if they are rarely mentioned in the specifications?
To make matters more confusing, The Consumer Reports issue of January 2022 lists 4 preferred systems for under-sink installation but none of these seems to have a RO component. I even find a single cartridge filter system from the well-regarded Impact Water Products. Their Solo 1 has a unique 3-stage cartridge but its daily purification capacity is 5-10 times what an average household like mine requires. What are the circumstances under which RO is necessary for city-supplied water?

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Some of our experts advise buying only US-made products but where can one find US-made water purification systems when most manufacturing has been outsourced to countries with cheap labor?
Over the years I have benefited tremendously and learned much from these forums. Please forgive me for my expression of helplessness but all I am hoping to find are some concrete recommendations for a kitchen water purification system for my city-supplied (soft) water that does not waste more water than it produces in purified form, serves our needs for drinking and cooking at about 5-10 gallons per day, and uses non-proprietary filters. Is that too much to hope for without having to learn the science of water purification and doing plenty of research worth publishing in an industry journal?
Thank you all for your insights.
 
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Bannerman

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Some of our experts advise buying only US-made products but where can one find US-made water purification systems when most manufacturing has been outsourced to countries with cheap labor?
It's not where the product is manufactered that is essential, but is the quality standard of the product and the company that provides the after sale backup and warranty.

Apple is a US company, but most of its products are currently produced by FoxConn in China to Apple's stringent specifications. If you experience an issue with your iPhone, you don't contact FoxConn in China as it is an Apple product, so you would only need to contact a local Apple service center. There are plenty of iPhone knockoffs produced overseas to various qualities, but if you experienced an issue with any of them, you could find the manufacterer is impossible to identify, and if found, you may find they ignore any communications regarding after sale support.

With any water treatment equipment, high quality and compliance to North American safety standards is essential as a component failure may result in considerable damage to your home. When failure of such equipment occurs, you may find your home insurance may not provide coverage, and obtaining assistance from an offshore manufacturer will be highly unlikely.

Many low cost off-shore produced water softener resins and filter medias are extremely low quality and may actually be unsafe for treating water for human consumption, even as the sales info may claim compliance to NA safety requirements.

Our home water supply is well water from our local municipality. Our local wells contain some measure of arsenic, fluoride and other unwanted contaminants, plus chlorine is added for bacteria control, and there is additional Sodium added by our softener as related to the 22 GPG water hardness. We choose to utilize a Reverse Osmosis system to obtain the highest purity for drinking/cooking. Since the RO membrane does not accumulate contaminants, those contaminants must be continually flushed to drain as they are stopped from passing through the membrane. We do not consider the flow to drain to be a waste, but is part of the cost of obtaining highly purified water.

Activated carbon is a fantastic filtration media that is highly effective for removing a wide range of contaminants. RO systems are commonly equipped with at least one carbon cartridge prior to the RO membrane, and another carbon cartridge for 'polishing' the water directly before flowing to the RO faucet or water dispenser.

Depending on which contaminants you wish to remove from your municipal water, you might choose a system equipped only with one, two or three stages of carbon block filtration cartridges with the final stage having the smallest micron number.

Even if using only a carbon filtration system, recommend installing a separate RO type faucet for dispensing that water. To be most effective, contaminants will need to have sufficient contact time with the carbon for complete adsorption to occur. A small faucet will typically limit the flow rate to 1 GPM, thereby allowing the small quantity of carbon in the cartridge sufficient contact time to allow contaminants to be adsorbed by the carbon pores.
 

Breplum

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With city supplied water, you should be able to look up the exact test results for water quality that every municipality generates.
For example, over here on the coast our supplied water is incredibly good except for the notable addition of Chloramine and its breakdown product trihalomethanes.
For this catalytic carbon filtration is ideal, but, long contact with any good charcoal filter (as you get for a semi-slow flowing kitchen drinking water dispenser (and we like to pipe the filtered water to the fridge as well)).

We don't need any pre-filters at all. Fugedabout RO with good city water.
The wisdom of Bannerman is fact: " To be most effective, contaminants will need to have sufficient contact time with the carbon for complete adsorption to occur. A small faucet will typically limit the flow rate to 1 GPM, thereby allowing the small quantity of carbon in the cartridge sufficient contact time to allow contaminants to be adsorbed by the carbon pores."

I personally own the Multi-Pure (26 years), and use it with ISE insta-hot dispenser. Very happy. Change cartridge with generic match every year.
 
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Reach4

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Many cities don't even publish hardness.
 

Rmk9785e

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<Snip>
Depending on which contaminants you wish to remove from your municipal water, you might choose a system equipped only with one, two or three stages of carbon block filtration cartridges with the final stage having the smallest micron number.

Even if using only a carbon filtration system, recommend installing a separate RO type faucet for dispensing that water. To be most effective, contaminants will need to have sufficient contact time with the carbon for complete adsorption to occur. A small faucet will typically limit the flow rate to 1 GPM, thereby allowing the small quantity of carbon in the cartridge sufficient contact time to allow contaminants to be adsorbed by the carbon pores.
Thank you for an easy to understand explanation.
I took the first step of figuring out the contaminants in our municipal water supply. The most recent report from 2021 shows the water supply meets or exceeds standards. If I read it correctly, the TDS range from 89-314 mg/L. Chlorine as CL2 ranges between 0.04-7.93 mg/L. Hardness is reported between 23-216 mg/L. We tested our water at the tap for hardness using HACH 145300 test kit and it varies between 3-5 gpg and therefore have not seen a need for a water softener. Water at the tap tastes fine but just to be on the safe side, we want to keep an RO system under the sink which we inherited when we bought the house 11 years ago and have been maintaining it. It's time to replace it and hence looking at our options.
Here are our requirements for the new system we want to acquire:

- No more than 4 stages
- High recovery Dow style RO membrane
- 2x10 prefilter housings using non-proprietary filter cartridges
- 5-50 gpd capacity
- Flow rate of 0.5-1 Gpm
- Faucet with airgap
- WQA and/or NSF certification
- Easy indication for required filter change and possibly high TDS indicator (Nice to have but not required)

The questions I'm contemplating are:
1- Do we need an RO system with our municipal water quality or would a filtration system sans RO will suffice?
2- If an RO system is recommended, which brand and model should we be looking at to meet the above specs?
3- Should we consider a whole-house carbon filter system in addition to an under-the-kitchen-sink system?

This is one of the best knowledge sources and forums with generous experts willing to share their advice. I wonder if the site owners would consider periodic reviews and recommendations just like Consumer Reports, Spruce, and others for plumbing-related products?
 
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Gsmith22

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From #1:
The experts may know it all but for the commoner, the discussions and options are baffling without some clear answers. If would be nice if the collective wisdom here would narrow it down to the top 5-10 configurations and the topic is stickied for all new inquiries but clear choices are hard to find even after going through lengthy threads.

There are no top 5 configurations because 1)water is infinitely variable so one person's problem is different than the next 2)there are different pollutants being addressed as well as different levels of said pollutant from one person to the next and 3)there are multiple processes that attempt to deal with the same pollutant with different pluses/minuses or outcomes depending on what happens to be in the water in addition to what you want out of it. All of these variables contribute to the no one size fits all problem that is making you feel "helpless". What you really need to do is determine what substance(s) you want removed from your water, next determine what processes can remove that substance, and then are there any undesireable outcome of using that process. I'll give an example: someone has hard water with low pH. So they put in a water softener to lower the hardness, but then to deal with the pH, they run the water through a neutralizing media such as calcite. The calcite then adds hardness back to the water so they ended up with hard water again (although pH was raised). You could try a different order to the process (raise pH first followed by hardness reduction) but that can require larger softener or mess with effectiveness of softening (processes work differently at different pH). Or you could switch one of the proccesses - use soda ash injection instead of calcite to raise pH and not add hardness. Soda ash requires more work and is probably more expensive. Its a better process but someone may balk at it because of the added work/expense. So with just this one simple example, there are multiple ways to come to a solution with differeing results and differeing costs/homeowner maintenance. The best way to go about this is determine what is a problem that you want removed, what are the potential ways to remove it, and what are the drawbacks to each method.

From #1
Some of our experts advise buying only US-made products but where can one find US-made water purification systems when most manufacturing has been outsourced to countries with cheap labor?

Bannerman handled this well in #2 but the short answer is, US made is a way to near guarantee NSF standards are met and there is after purchase service available to you (troubleshooting, parts, etc). foreign made and intenet purchased is a quick way to assure no after purchase service and potentially not up to NSF standards (depending on what is purchased and who from). Stick to name brands (Fleck, Clack, Pentair, etc.) and you probably won't have a standards issue; internet purchase will probably result in an after purchase service dissapointment.

From #3:
The questions I'm contemplating are:
1- Do we need an RO system with our municipal water quality or would a filtration system sans RO will suffice?
2- If an RO system is recommended, which brand and model should we be looking at to meet the above specs?
3- Should we consider a whole-house carbon filter system in addition to an under-the-kitchen-sink system?
1) I would hazard to say no municiplally supplied water would ever require RO ( I know Flint, MI). Municipal water suppliers have to meet federal and state EPA standards for drinking water quality so it would be the rare exception that something elaborate is needed to drink municipally supplied water. Most issues with municipal water are "secondary" contaiminants (as defined by EPA) such as hardness, low pH, clarity, taste, smell, etc. They don't cause sickness but maybe aren't ideal for your piping, look refreshing, or taste great.

2)You mention TDS, Chlorine, and Hardness. TDS is total dissolved solids - I don't think you want to remove all solids as pure water is very caustic to you internally and your plumbing. RO will remove nearly all solids. Typically ROs include reminerization filters to put the minerals back in solution but unless some of that TDS includes harmful materials, I don't get what is trying to be achieved here. Chlorine is from municipal water treatment - most use carbon filtration to remove that (if you even deem that necessary) and hardness is best removed by a water softener. You typically want soft water to be run through an RO anyway (hardness clogs up the membrane) so I don't see anything here that would benefit from RO.

3)Based on what you listed as "problems", that would probably be the most effective thing to remove Chlorine and its byproducts. Softener if you deemed the water too hard.
 

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I really would like to hear more about this.
water is known as the "great dissolver" for a reason. it doesn't like to stay pure. Water will tend to dissolve whatever it comes in contact with regardless of its pH (although low pH contributes to this property). The more things dissolved in water (ie high TDS), genearlly the less active this property. RO, by its natured/design, removes dissolved substances, the water becomes very pure when processed in this manner, and thus agressively dissolves things it comes in contact with. RO systems typically include reminerization filters to add back minerals removed by the RO to stop this. There are various indices that try to measure the "activeness" of the water - Langelier Saturation Index (LSI) is a common one.
 

Reach4

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You should not run RO water thru metal pipes. However I don't think there is a problem drinking it.
 

Bingow

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However I don't think there is a problem drinking it.
No problem here drinking RO for 20+ years. However, my wife with her far more sensitive taste ability, mostly drinks DISTILLED water, to avoid the trace salt she is able to detect in our RO water. FYI, we are on a well, with extremely hard water, ranging from 60 to 88 gpg throughout the year, and so we use a softener.

Medical references we have found online say no problem drinking distilled (pure?) water, they only mention that our taste buds usually prefer some minerals as opposed to none. I would like to see an objective source that says otherwise.
 

Bannerman

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to avoid the trace salt she is able to detect in our RO water
While a softener will increase the amount of sodium bicarbonate, there is no salt (sodium chloride) in softened water as the ion exchange process will remove hardness ions (mainly calcium & magnesium), replacing those ions with a proportional quantity of sodium ions. During regeneration, the higher concentration of salt brine will cause hardness ions that are adhering to the resin to be released, replacing them with sodium ions that will then adhere to the resin beads. The hardness ions that are released, are flushed to drain along with the chloride from the salt brine.

Since RO membrane is especially efficient at removing sodium from water, RO is the recommended sodium removal method when a softener is removing a substantial quantity of hardness.

See short writeup at the lower left at this link: How much sodium is in softened water
 
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Bingow

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Thank you @Bannerman for the tutorial, which I genuinely appreciate. I won't strike up yet again another argument with my fair wife, as her senses of smell, taste, and hearing all far exceed mine. She tastes a difference between RO and distilled H20 and describes it as... something salty. No one on earth will convince her otherwise. OTOH, when I taste softened (not RO) water from our kitchen faucet, it has a hint of... salt. No one on earth... (etc). Maybe there's a component of our very high TDS (over 1,000) that plays tricks on our taste buds, and for lack of having a wine taster's discrimination, call it salty.
 

Reach4

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I think that our well waters have chloride, which are chlorine ions... 50 mg/l in mine. Maybe your levels are lower. MCL for chloride is 250 mg/l. Our raw water has sodium ions. Our softened water has even more sodium ions than the raw water, because the calcium and magnesium ions have been replaced by sodium. So our softened water has sodium chloride salt in it IMO. But wait, those are ions. Does that count? I think yes. Add pure sodium chloride crystals to distilled water, and the ions go into solution, producing sodium and chlorine ions. You would agree that that solution has salt in it, right, even if you use the narrowest definition of salt.
 

Bingow

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Somewhere in this forum I have buried our water Q report, but yes, our chloride came in at 290 mg/l. Sulfate was way high at 730 mg/l, and sodium 170 mg/l, if that might have a bearing on after-softening taste. Chemistry was my worst subject, still is, but in the end it's what we "think" our water tastes like that rules the day, subjective vs objective.
 
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