Water filtration

paulraphael
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Wed Apr 18, 2018 4:17 pm

Hello,

I'm new to this forum, and am hoping someone can solve rather odd mystery with water quality. Apologies in advance for too many details.

A bit of background: I enjoy many loose-leaf teas, but my daily, lazy go-to tea is Taylors of Harrowgate Scottish Breakfast tea in bags. Please don't judge! It wakes me up in the morning, and I enjoy the very robust flavor and syrupy body and ample tannins. And it's easy. I live in Brooklyn, where water quality is generally very good, with low hardness and few contaminants. I've always filtered the water with a Brita filter to remove chlorine and the nasty flavors from my building's old pipes.

A couple of weeks ago, as a general upgrade, I installed under-sink filtration. Just a generic 10" filter housing, with a Pentek carbon block filter. The one I picked had a 1/2 micron pre-filter (which I don't need ... it just seemed like a good idea). The water came out of this tasting flat. The tea tasted very, very flat. Thin body, weak flavor, almost all the tannins gone. This seemed odd to me because the carbon filter shouldn't be doing anything besides removing particulates and organic chemicals. It should be leaving the minerals and pH alone. My understanding is that Brita filters have an ion exchange resin that slightly reduces hardness, but that this resin wears out quickly and becomes mostly inactive if you keep the filter around a long time (which we do).

So I did some research, and discovered that TDS (total dissolved solids) has an impact on flavor, and that it actually includes suspended solids that are smaller than 2 microns. Which means that my filter was stripping out some of the TDS. So I swapped for a filter from the same company—a carbon block filter that only filters down to 5 microns. This made an immediate difference. Drinking water is now insanely delicious. But the tea, while better, still tastes flat to me.

I'm wondering if the Brita water may actually be brewing defective tea, and that I happen to like the defects. Here's why: the package instructions say to brew the tea 4-5 minutes. If I do that, it's undrinkable. I have to brew this tea for 2 minutes to get the bold flavors I like. (This is not the case with other teas. The Lapsang Souching loose leaf tea I like is best after 5 minutes). So for some reason the Brita water seems to aggressively extract the Scottish Breakfast blend.

With my new filter, I need to brew it a full 5 minutes. I get some body, decent flavor, and just a hint of tannins. Mostly it tastes smooth and clean. There's total clarity in the cup. Possibly someone who knows tea better than I do would say "this is how it's supposed to be." But I'm not sure. And I miss the big flavor of the tea from the Brita water.

Obviously I could keep the Brita around just for brewing tea, but I'd prefer to get to the bottom of this. Any idea what could be going on?

Thanks so much for your ideas. And for making it this far.
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pedant
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Wed Apr 18, 2018 5:48 pm

interesting post, thank you

i don't have direct answers, sorry. however...

i wouldn't pay much thought to the brewing directions on the packaging. most of us just ignore them :lol:
but the ~3min discrepancy between brita and your new filter is interesting. it does suggest that the extraction kinetics have noticeably changed.

could you take some untreated water from your bathroom sink or something and tell us how that performs? i realize it will taste more chlorinated, but still, what can you tell us?

also, have you considered getting a TDS meter?

maybe it could help you in your investigation

some work has been done on the effect of minerals and other dissolved solids on extraction kinetics, but it's mostly looking at coffee.
you could hit the literature some more i guess. i can't say for sure that it will help you improve your water or find out what's going on though.
here's an example: https://pubs.acs.org/doi/full/10.1021/jf501687c

you could also play with adding minerals to your water. maybe start with calcium and/or magnesium salts.
i know at least one person that does that for tea. also, many beer brewers do it.
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Baisao
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Wed Apr 18, 2018 6:57 pm

In addition to what Pedant has added, I would like go suggest that you aim for a TDS between 50 & 150.

Now to throw in something that is a bit mysterious to me: some trace minerals found in a certain Italian spring water will totally flatten a tea to the point that it has no astringency and can’t be forced to be bitter. The mystery is that I’ve compared the mineral contents of that Italian spring water to a domestic one and they are close enough in content and percentages as to be almost the same. The domestic spring water does not have this affect.

Further, I have a wood-fired kettle that changes the water noticeably no matter how it is heated: more body, slightly sweeter, and mutes astringency. Whatever the kettle is introducing to the water must be in the low ppm, yet the affect isn’t at all subtle.

I know this only adds to the conundrum but I mention it because I think it demonstrates that there is a lot we don’t know about how water affects tea.
paulraphael
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Thu Apr 19, 2018 7:57 am

Thanks so much for the input. And thank you Pedant for the link to that study; there's information there that I haven't seen elsewhere. I like coffee, too, so this may be helpful even if doesn't describe the tea issue.

I don't have a way to test TDS, but may pick up some test strips. I did test the pH, and found no differences between the new filter, the old filter, and water from the tap.

And yes, I did try brewing with water straight from the tap. It mostly tastes dirty, if that's a reasonable description. At the moment I think it's less about chlorine than corrosion and gunk in my building's old galvanized pipes. Underneath the dirt, though, it's a bit more like the new filter than the old filter. Which makes me wonder if the Brita is actually adding something to the water (via the ion exchange resin, or who knows what).

Adding some minerals sounds like a great experiment. I was about to grind up a calcium supplement but saw it was full of other stuff, including sugar. The drugstore probably has some pills that are pure CaCO3.

Yesterday I finally managed to make a good tasting cup of the tea from the new water. It required using a little less water relative to the tea, and brewing 4 to 5 minutes. I haven't been obsessive enough to taste this side by side with the Brita water, but it now tastes the way I remember, and is enjoyable.

Water is strange stuff!
Ethan Kurland
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Thu Apr 19, 2018 11:30 am

Baisao wrote:
Wed Apr 18, 2018 6:57 pm

Further, I have a wood-fired kettle that changes the water noticeably no matter how it is heated: more body, slightly sweeter, and mutes astringency.
Those effects are good for me for some teas. Any more information on that kettle?

And talking about mysteries.
Water from my tap is fine for drinking & cooking, but water that has been filtered by my Big Berkey (ceramic filters) makes more flavorful tea by far.
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pedant
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Thu Apr 19, 2018 9:01 pm

paulraphael wrote:
Thu Apr 19, 2018 7:57 am
I don't have a way to test TDS, but may pick up some test strips. I did test the pH, and found no differences between the new filter, the old filter, and water from the tap.
i would really recommend a TDS meter like the one i linked to in my previous post instead of test strips intended for pool/spa.
meters are cheap and give much higher resolution.
paulraphael wrote:
Thu Apr 19, 2018 7:57 am
Adding some minerals sounds like a great experiment. I was about to grind up a calcium supplement but saw it was full of other stuff, including sugar. The drugstore probably has some pills that are pure CaCO3.
i somehow doubt you'll find pills that are pure. typically, antacid tablets are flavored and have binders added.
consider buying some pure gypsum (CaSO4) and epsom salt (MgSO4) online or from a drugstore.
see also http://babelcarp.org/babelcarp/fakemineralwater.html
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mrmopu
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Thu Apr 19, 2018 9:17 pm

I know this is a link to another site but you may find some info in it.

https://steepster.com/teaware/abundant- ... ion-filter
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Baisao
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Thu Apr 19, 2018 10:23 pm

paulraphael wrote:
Thu Apr 19, 2018 7:57 am
I don't have a way to test TDS, but may pick up some test strips. I did test the pH, and found no differences between the new filter, the old filter, and water from the tap.
I agree with Pedant regarding the TDS meter. It’s a simple resistance circuit scaled for TDS. Works well on all waters I’ve used it on, accurately reporting back their stated TDS.

paulraphael wrote:
Thu Apr 19, 2018 7:57 am
Adding some minerals sounds like a great experiment. I was about to grind up a calcium supplement but saw it was full of other stuff, including sugar. The drugstore probably has some pills that are pure CaCO3.
Easier and safer than that would be to blend waters. As an experiment try blending in half Aqua Panna with a low TDS water like Voss. Compare that to just Voss. The results should be startling.
.m.
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Fri Apr 20, 2018 1:41 am

I dont have any experience with under the sink filters, but i've been using ceramic tabletop gravity filters (Doulton sterasyl, black berkey) for several years with a good experience. These claim a similar micron rating to yours, about 0.9 absolute and anywhere between 0.2-0.8 nominal. And they dont change the hardness of the water in any significant way, so i'm a bit surprised that it would happen with carbon blocks. I would think one would need a reverse osmosis system for that.
One think to mention, these filters may require some priming or a some time for the taste to settle down. They also need regular cleaning: whatever they filter out will accumulate inside them, i might imagine that passing water through a bit of "gunk" might not have a good effect. But that shouldnt be your issue since your unit is fairly new.
.m.
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Fri Apr 20, 2018 2:05 am

Baisao wrote:
Wed Apr 18, 2018 6:57 pm
Further, I have a wood-fired kettle that changes the water noticeably no matter how it is heated: more body, slightly sweeter, and mutes astringency. Whatever the kettle is introducing to the water must be in the low ppm, yet the affect isn’t at all subtle.
The effect of clay or cast iron kettles on water is very intriguing. I wish somebody could shed some light on the mechanism.
1) Is it acting by enhancing the water through dissolution of minerals?
2) Is it acting as a catalyst for some sort of chemical change in the structure of the water (such as oxidation of some components for example)?
3) Is it the porosity of the material that somehow influences the amount of dissolved oxygen in the heated water?
4) Or is it some other mechanism?
A lot of questions...

[Sorry to be offtopic, but i guess it is all related.]
paulraphael
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Fri Apr 20, 2018 1:06 pm

.m. wrote:
Fri Apr 20, 2018 1:41 am
I dont have any experience with under the sink filters, but i've been using ceramic tabletop gravity filters (Doulton sterasyl, black berkey) for several years with a good experience. These claim a similar micron rating to yours, about 0.9 absolute and anywhere between 0.2-0.8 nominal. And they dont change the hardness of the water in any significant way, so i'm a bit surprised that it would happen with carbon blocks. I would think one would need a reverse osmosis system for that.
I don't think the under-sink filter is doing anything to the hardness, but it may be doing something to the TDS. According to what I read, TDS includes suspended particles smaller than 2 microns, which a 1/2 micron filter would definitely reduce.

So this is just my working theory on why water from my 1/2-micron carbon block filter tasted flat, while water from the same brand 5-micron carbon filter doesn't. Tea is also better with the 5-micron filter, but still seems to extract much more weakly than from Brita-filtered water.

The Brita water may be the mystery factor here. It has some ion-exchange resin that can reduce hardness (as a side-effect). It's there for removing heavy metals, which testing shows that it's not very good at. I've also seen tests that show the water softening effect to be very short-lived. We kept using our Brita filters well past their nominal life. With tea, I never noticed flavor or extraction changing as the filters got older. I'd just notice the filtration getting slower and slower.
paulraphael
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Fri Apr 20, 2018 1:12 pm

.m. wrote:
Fri Apr 20, 2018 2:05 am

The effect of clay or cast iron kettles on water is very intriguing. I wish somebody could shed some light on the mechanism.
1) Is it acting by enhancing the water through dissolution of minerals?
2) Is it acting as a catalyst for some sort of chemical change in the structure of the water (such as oxidation of some components for example)?
3) Is it the porosity of the material that somehow influences the amount of dissolved oxygen in the heated water?
4) Or is it some other mechanism?
A lot of questions...

[Sorry to be offtopic, but i guess it is all related.]
I'd be interested in this as well. I'd rather solve this with a teapot than with some esoteric water remineralization sideshow.
Ethan Kurland
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Sat Apr 21, 2018 4:47 pm

.m. wrote:
Fri Apr 20, 2018 1:41 am
....Ii've been using ceramic tabletop gravity filters (Doulton sterasyl, black berkey).... And they dont change the hardness of the water in any significant way,
.m. When my regular Berkey filters need replacement, I might buy the black ones now that you say hardness of the water is not changed in any significant way. I have assumed that the black filters which remove lead & chlorine that the regular filters do not remove would also filter out all the minerals that flavors of tea use to give water its flavor. I tried distilled water & as others have done, tea that was close to tasteless.

Another ? for you .m.: how many years of usage are getting from the black Berkey filters?

Thanks
.m.
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Sun Apr 22, 2018 4:43 pm

Ethan Kurland wrote:
Sat Apr 21, 2018 4:47 pm
When my regular Berkey filters need replacement, I might buy the black ones now that you say hardness of the water is not changed in any significant way. I have assumed that the black filters which remove lead & chlorine that the regular filters do not remove would also filter out all the minerals that flavors of tea use to give water its flavor. I tried distilled water & as others have done, tea that was close to tasteless.

Another ? for you .m.: how many years of usage are getting from the black Berkey filters?
I had been using the Doulton ceramic one for about 4 years, then it went to storage when i had to move across the atlantic. The Black Berkey i've had for about year now. I've just had to soak it in vinegar recently since it was getting clogged (the water is on the hard side here) and started to grow some mold. I haven't compared the two filters side by side, and the water is quite good here so it would be hard to say which is better. I can only say that the quality of the filter parts seem higher on Doulton. I also find the marketing of the Berkey filters a bit sketchy, and wouldn't necessarily trust their claims. Anyways, i've been happy with both, and in places with not so great water, or heavily chlorinated one, they make a substantial difference.
paulraphael
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Fri Apr 27, 2018 10:59 am

I've been doing some pretty cool mineral experiments. I'm basing them on some semi-scientific articles on water quality for tea, and on the DEP report on mineral content for Brooklyn water.

Most of what I read suggests that black tea does best with around 68 mg/l total hardness. Hardness is a composite of calcium and magnesium ions in water, but tea does best (in most people's opinion) without magnesium. This makes it somewhat unlike coffee, which likes some magnesium.

Our water has around 13mg/l calcium hardness (low) and and 4.6mg/l magnesium hardness (very low, but not zero).

So I did some math, and came up with a solution of calcium chloride. An eye dropper-full of this in a mug will raise the total hardness of the water to 68g/ml. This includes the bit of magnesium that's already in the water.

The resulting tea tastes great! It's similar to tea made with the Brita filter water, although a bit more round tasting ... maybe slightly more full-bodied and slightly less tannic. It extracts very differently. I have to go the full 4 minutes. Twice as long as with the Brita water. I also can't reuse the same tea as often as with the Brita water.

The Brita water must be extracting tea more aggressively. The reasons remain a mystery (I don't have the means to test this water). It would seem that the Brita filter actually adds minerals (or something) to the water, which doesn't make any sense. The ion exchange resin should be adding a tiny bit of sodium, but that part of the Brita filter isn't very strong, and on my current filter is probably completely dead.

So I'm still befuddled by some of the original questions, but have managed to learn a bunch about water, and have a not-too-annoying way to get delicious tea.

Tweaking coffee water is the next project. Also trying the minerals with some other teas.
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