Hydrogen-enriched water can be created by dissolving magnesium tablets, which release gas and should be consumed within 5-15 minutes after the tablet dissolves.

“it turns out that you can create hydrogen enriched water by putting tablets of magnesium itself, small amounts of magnesium dissolving those in water. It will give off a kind of gaseous solution. You'll see a bunch of bubbling in there. You certainly want to dilute that tablet and then consume the water. And yes, it's true what you've heard about and read from these commercial sources. You do want to consume that water within about, you know, five to 15 minutes after that tablet completes dissolving.”