Mcallen, Texas
Not resolved

Update by user Dec 20, 2016

OK, after a year and half of continuous experience on the Zero Water filter and browsing all replies following my review so far, I think I have a deeper understanding of the "problem" of this product.

I mentioned that the TDS reading of the tap water in the city I was living (McAllen, TX) was about 700 and each Zero Water cartridge did not filter more than 5 gallons of water there. Now I have moved to the Nashville area in TN, where the TDS of tap water is just a little over 100, indicating much less ions contained in the water (very good quality).

The old cartridge which already filtered 2 gallons in TX continued to give me about 15 gallons more of clean water in TN before it turned sour. Then I tried with a brand new Zero Water cartridge and it has filtered 28 gallons of water and so far it is still keeping the TDS reading at 0 after filtering. Therefore, the acidic taste at the end of the lifetime of a filter cartridge seems to reflect a capacity "problem" instead of a quality problem.

To further explain this "problem", the cations (ions carrying positive charges) and the anions (ions carrying negative charges) in water are always equal in the number of charge. Cations may include calcium ion (Ca 2+), sodium ion (Na 1+), potassium ion (K 1+), magnesium ion (Mn 2+), and so on.

Anions may include sulfate ion (SO4 2-), chloride ion (Cl 1-), carbonate ion (CO3 2-), and so on. The numbers at front of + and - signs denote the number of charge each ion carries, but this is not important if you don't care about the detail. The Zero Water filter contains an ion exchange layer, which replaces the cations with hydrogen ion (acid ion, H 1+), and replaces the anions with hydroxyl ion (basic ion, OH 1-). As you may already know (H+) and (OH-) form pure water H2O.

This is how the filter gives you pure water. Everything is fine until either ion, (H+) or (OH-), is depleted in the cartridge. In our case the hydroxyl ion (OH-) is fully consumed first, and then the anions remain in the water after filtering, and the cations are still replaced by the hydrogen ion (acid ion), finally resulting in acids, such as sulphuric acid (H2SO4), hydrochloric acid (HCl), carbonic acid (H2CO3), and so on.

That's why the water tastes sour or acidic at the end.

Finally, my suggestion is, if the TDS reading is high in your area, it may be economically preferable to just buy water from supermarkets. If the TDS values is low, Zero Water is a convenient option.

Original review posted by user May 23, 2015

I am a chemist and a polymer expert. I know what ion exchange is. I had the same sour/acidic taste experience with ZeroWater. It seems to me a design problem of this product.

Background 1: What does a filter capture?

Many other branded filters, such as Brita, DO filter some harmful organic chemicals in water using activated carbon. They don't do anything with the salts in water (not only the sodium chloride used in cooking). General salts in water are not harmful, but they don't taste good at a high concentration. ZeroWater captures cations and anions in water using the ion exchange technique, so that the salts are filtered.

Background 2: What do you know from TDS number?

The TDS meter coming with ZeroWater tests the conductivity of water. That is, it only measures the concentration of salt/ion in water instead of all solids, and estimates the amount of total dissolved solid in water. The water with a 0 reading on the meter can still contain some organic chemicals. Anyway, it's reasonable to believe the total solid left in water is very close to zero based on the so-claimed 5 stage filtering technique including an activated carbon layer. However, a totally pure water is not good to health in fact. If you read a TDS value of 30 from a bottled spring water, it doesn't mean the water is not good. Instead, the water contains some minerals/salts needed by your body. Sometimes I added a small fraction of Brita filtered water in the ZeroWater to tune it to below 50 TDS.

Problem of ZeroWater:

After flushing the ZeroWater filter I started to enjoy the filtered water, which was much cleaner than the tap water (TDS around 700). However, after about 5 gallons of water were filtered, the filtered water turned bad and tasted extremely sour/acidic as many people had experienced. I noticed at that time that the flow rate of the filter was faster than before and some gas bubbles came out from the orifice at the bottom of the filter. The sour taste indicated there might be still a large amount of hydrogen ions available in the filter, and the filter should still have a considerable lifetime. It seemed that some structure in the filter was crushed because of the build-up of filtered substance or increased pressure inside, so the chemical holding hydrogen ions leaked out. The flow rate might be much faster due to the damage, taking out the small amount of air that would be otherwise locked inside the filter.

Hope this comment is useful to both the users and the engineering department of ZeroWater.

Product or Service Mentioned: Zerowater Filter.

Reason of review: Bad quality.

Monetary Loss: $40.

Preferred solution: Let the company propose a solution.

  • Sour Taste
Do You Have Something To Say ?
Write a review


You will be automatically registered on our site. Username and password will be sent to you via email.
Post Comment

Thank you to the two above commenters. I have a much better understanding but still not quite sure how to get the TDS rating prior to purchasing a new unit.

I have experience with Zero filtering unit which required changing faucet head and using their hose to pitcher.

Seeking larger container to filter NYC tap water, which used to be so good. Suggestions on either testing or best unit?


Thank you for explaining this for everybody. When i test the Water from a used Zero Water filter it reads more than the New Jersey tap water, which is at around 375 here. Thank you.


Wyou might find this YouTube clip useful...


I bought the biggest container of zero water, the filter started giving me sour water after about a gallon and a half. This was a 40 dollar item, most people would shrug it off, but I simply can not afford to do this. I had faith in the product, now I don't.


I have decided ZeroWater pitcher is not for me after reading these reviews.


I've had mine for over a year and love it. It depends on where you live and what toxins are in your area.

The water here is already pretty high rated - I've not had to change my filter yet and clean I clean the pitcher regularly. No mold, no issues. It's perfect for me. The water tastes good.

I live in an apartment, so don't want to install a major filter system.

This is the best rated of all water filter pitchers and I can see why. There's always going to be folks who will have issues for various reasons, but I've had no issues at all.




I purchased my refrigerator container with my Zerowater filter and my little tester from Walmart for north of $40. After just about three weeks using it for my coffee maker my wife put water in a glass for me and it tasted like saltpeter.

I tried contacting Walmart they said contact ZeroWater, it just wasn't worth the hassle. It still sits on my counter to this day.

The other issue is with their tester it lasted all of two weeks before the batteries died and there is no way to replace them. Very unhappy with an expensive transparent counter decoration.


I am so sorry I didn't research better. The reviews on Amazon gave no indication this was a problem.

Shame on ZeroWater for not addressing this issue. The water is DISGUSTING and can't be healthy for ANYONE!!!


So .. a.m glad i found your thread.

I thought i was wrong about the tingly lemon taste of my water all of the sudden (i live by myself so no other taste testers except my cats. As an aside, they have an aerated drinking fountain and once aerated, they will drink the water. They are extremely picky so i thought it was still ok.) I washed the pitcher, my water container in ther fridge, etc. No joy!

I then thought maybe i should not have left the filtration pitcher in the fridge??? Was some strange bacteria growing? I have used this filtration system less than a month - i live in San Diego 7 miles from the Mexican border. Few people drink tap water here!

My TDS reading was 674 without the system. It, of course, reads 0 now but the water is undrinkable straight due to the taste.

My question is - despite the taste, is the water safe to use in cooking or coffee maker? (Unfortunately i bought 2 new filters yesterday before reading this.) Maybe this is answered somewhere else and if so i apologize for being redundant.


Wow . Extremely HELPFUL .

I live in same city mentioned and it IS 700 TDS . So that explains it. So in Tennessee it IS much much lower. It also shows on the map that came with the filter .

Thank you so much for clarifying. Also great to know you have education in what you are talking about


I have a question for anyone here: If I don’t really mind the taste of the lemony water, is it okay to drink until I get new filters? Will it be harmful to me in any way? Thanks in advance!


Same issue here after about 15 gallons of tap water (TDS 128). If I have to buy filters at this rate, I will go back to my Brita fds


I have looked this up because our filter is only working for 2 weeks, I am about 625 reading to start. I am buying water until we get back to Colorado.

Then I will try it again. The filters are way to expensive to keep buying and replacing every 2 weeks.

The worst part is my old put pitcher did not make my water taste bad after 2 weeks it filtered for at least 2 months before changing. I am not happy.


So very disappointing After only just over a week Water is as sour as if I had added lemon What a waste

@Cathy Mo

Oh thank God i really thought some lemon juice got in one of my jugs that I filled up to keep refilling my big pitcher.


I will never buy this product again!!!!!!!!!! Filter is a waste of money!!!!!!


Agree with last few posts. Water tested here >300. After ZeroWater filter


*** this product. I replaced the filter not even a week ago and it already tastes like the water equivalent of sour milk. I'm glad I'm using it as the guest in someone's house and that I didn't make the mistake of buying it myself.


thanks for explaining why zero water gets this sour taste. The city I live in has pretty good water and the meter read it in the 400s to 650 out of the tap.

However, for the cost of the filters they do not last long enough for me. I'm going back to Brita that does not taste like something toxic when the filter starts to dump leftover chemicals into the water.

Yuck. Thanks again for the article.

Zerowater Reviews

  1. 158 reviews
  2. 77 reviews
  3. 35 reviews
  4. 29 reviews
  5. 30 reviews
Zerowater reviews