This post concerns water and tea. Allow me to begin with an analogical
digression.

Several decades ago, as a pre-professional nerd, I read that sugar is
critical in many foods not as a source of sweetness per se, but as a
flavor potentiator like unto salt or MSG. This seemed possibly relevant
to the consuming problem of rapid flavor decay in so-called Juicy Fruit
gum. So I took a wad of post-sapid chicle, wrapped it around a pinch of
table sugar, and was astonished to find it entirely revivified.
Fortunately for Wrigley's fortunes (and my remaining teeth), I was too
lazy to make this a regular practice, and none of my cohort expressed
interest in such a life-extension methodology.

Back to tea: I keep being disappointed on home-brewing rare and fine
wonders that delighted in-store or at others' homes. Water is clearly a
factor, most likely due to absence of needed solutes rather than
presence of contaminants. But I'm too lazy and cheap to schlep gallons
of bottled solvent, and also (after several years in the UK) averse to
de-scaling the kettle. So of late, I've been trying some post-brew
experiments. These have taken the form of adding a dash of bottled water
to the gaiwan before dousing with hot tap water. I use mineral rather
than spring water, to get a good slug of ions in the small addendum.

This has worked pretty well. So far, I've used Gerolsteiner, which may
not be an optimal mineral balance. (It is, however, the only one
available here in the woods.) It's still less than convenient, and makes
it that bit harder to control brewing temperature.

So recently I've tried adding mineral water to the finished brew. This
goes against common wisdom about the effect of various solutes
(including oxygen) on extraction chemistry. -Common wisdom, I might add,
absent widely published evidence. Thus far, the effect has been just as
beneficial. Today, for example, I brewed a sample of Old Dong Ting from
NYC's wonderful Tea Gallery. (Disclosu commercial connection; I spend
money there at every opportunity.) This exquisite tea went "flat" after
just three steeps in tap water. Adding a few ml of mineral water to the
poured cup added/restored multiple layers of sweetness, fruit,
complexity. And seemed to smooth over hints of roughness, somehow
bringing the smoke/roast into better balance with more intrinsic leaf
notes. (Kind of like the difference between 10- and 15-year-old
Laphroaig, for those of that persuasion.) I took out five more very
tasty steeps before going out to grease the Kioti.

Now, here's the punch line: the bio-effect of a little added mineral
water seemed to persist. I alternated "spiked" and tap-water brews,
rinsing the cup between, and found them almost indistinguishable.
Perhaps this shouldn't be surprising: calcium is a dominant mediator of
cellular and neural activity, and charging the taste buds and proximal
tissue with divalent ions might have a persistent effect. Any biologists
here able to comment?

Anyway, the provisional conclusion: a very small addition of minerals
can apparently have a profound, persistent and positive effect on
perceived quality in brewed tea, without much effort. Your mouthfeel may
vary.

-DM