What difference does oxygen content of tea water make?

I agree with your suspicion. While boiling water most likely does cause it to lose some of its oxygenation, the bubbles and steam you see while boiling water do not come from the oxygen trapped in the water.

Water boils when you heat it enough for the water to begin acting as a gas. The reason boiling water bubbles is because the heat source is generally on the bottom, so the first water molecules to become gaseous are on the bottom and then bubble up.

Saying boiling water releases its inner oxygen is akin to saying that ice is not water and in fact simply traps water inside.

If you're worried about oxygenation, try pouring your cup of tea in various methods:

1. boil it in the mug (microwave?)
2. boil then pour into a cup
3. boil then pour a few times in to a cup
4. get a straw and blow some bubbles in your cup
5. try using seltzer water to make tea...?

Anyways, I could be wrong, but the whole concept seems a little silly.

Happy tea drinking :]

All moving water has dissolved oxygen in it. That is what fish breath

Dissolved oxygen is reactive, and will most likely extract more substances from the tea leaf, than without it. If these are the good flavour parts of tea, I do not know?

When you heat water it starts to release the dissolved oxygen. The more you heat water the more oxygen escapes

You can buy tea making kettles that bring water up to 95°C (203°F), but not boiling, so as to decrease the amount of dissolved oxygen lost, but still making the water hot enough to brew tea. They also save energy :-) I use one of these, and am happy with it

Example Kettle

Some people "watch" their kettle, and switch it off just before the water boils!

It is a personal taste preference if tea tastes better when brewed in water with more dissolved oxygen or not

All the correspondents seemed to have mislaid the chemistry and physics from early school lessons as I remember water is composed of two atoms of Hydrogen and one of oxygen, if one were to remove the oxygen as suggested then to be sure we are left with H2 which at NTP (normal temperature and pressure) occurs as a highly flammable gas, plus you would need a chemical reaction (catalysis) or electrolysis to separate O from H2 , boiling water is simply heating water until the vapour given off equalises atmospheric pressure which is one bar or one atmosphere in old money, as a matter of interest Marks and Spencers have a message on their tea packets that boiling water removes the Oxygen, a case I think for appropriate legislation enforcement.

Tom Gilmore

This person found that increased oxygen in the water resulted in milder, less tannic tea:

https://cookingwithnumbers.wordpress.com/2016/01/09/does-oxygenating-water-improve-tea/

Rather than boiling and reboiling water, they oxygenated water by bubbling air through it - so it doesn't exactly indicate what the effect would be from repeated boiling.

My mom, who would have been 100 years old by now, always told us that reboiling the water leaves the water a bit "stale" tasting. She talked of "Free Oxygen", which I believe was her way of saying Dissolved Oxygen. I think DO is what fish actually get through their gills, which is why fish in a bowl need to get fresh water (with DO at high enough levels) in order to live. So - my theory is that tea is best when made with fresh water that hasn't been previously boiled. That's my 2 cents!