My tea tastes flat and I reboiled the kettle

In short

This is a rare troubleshooting entry where the honest answer is that the thing you suspect is probably not the cause. Reboiling does change the water slightly and the change is small; three other things that happen at the same moment are much larger, and chasing the reboil means not fixing them.

Likely causes, in order

Most likely first. Answer the question under each one before moving on — several of these look alike in the cup and are told apart only by what was done to the leaf.

1. 1. What reboiling actually does, and how much it matters

   Water chemistryInferred by TeaHQ, not established

   Check: Was the water boiled once earlier and boiled again, or was it boiled repeatedly over an afternoon?

   Fix: Boiling drives off dissolved gas, and water with less dissolved gas is widely described as tasting flatter. One reboil makes a small difference that most drinkers do not detect side by side. Repeated boiling over hours, with the same water concentrating each time, is a larger effect and a reasonable thing to avoid.

2. 2. The water sat in the kettle, which is a bigger variable

   Water chemistry

   Check: Had the water been standing in the kettle since yesterday?

   Fix: Standing water picks up whatever the kettle has to offer, including scale and any residue on the element. Fill fresh rather than reboiling not because reboiling is ruinous but because fresh water avoids the standing as well.

3. 3. It was not actually at a boil when you poured

   Temperature

   Check: Did you press the switch and pour a few seconds later, before it had come back up?

   Fix: A kettle reboiling from hot clicks off fast and is easily poured before it reaches temperature. For black tea that under-extraction is exactly the flatness being blamed on the reboil, and it is much larger.

4. 4. The leaf is stale and the water is a distraction

   Storage

   Check: Smell the dry leaf. Does it smell of much?

   Fix: A flat cup is far more often a flat tea. Check the leaf before rearranging your kettle habits — a stale tea tastes flat with fresh water too.

Brewing methods this applies to

• Western brewing (teapot or mug) — A small amount of leaf in a large volume of water, steeped once for a few minutes and then strained off. The approach most English-speaking drinkers already know, and the one most teas sold in the West are made for.
• Tea bag brewing — Pre-portioned tea in a permeable bag. The format was an accident of early twentieth-century sampling practice and became the dominant way tea is drunk worldwide, because it removes every decision except how long to leave it in.

Related problems

Sharing a cause category, a tea type or a brewing method with this one.

• My green tea tastes flat and looks dark in this house — A delicate green tea that tasted bright elsewhere comes out dull and heavy here, with a darker, browner liquor than it should have and none of its aroma.
• My tea tastes of chlorine, metal or the kettle — A chemical, swimming-pool or metallic note sits over the tea, and it is there whichever tea is brewed.
• We fitted a water softener and the tea got worse — Since a softener was installed the kettle stays clean and the tea tastes flat, slightly salty or oddly soft, with the brightness gone.
• I bought a water filter for my tea and it changed nothing — A filter jug or tap filter was bought specifically to improve the tea, and the cup tastes the same as it did before — with the same dullness, the same film and the same scale in the kettle.
• I filtered my water and the tea got worse — After switching to filtered, distilled or reverse-osmosis water the tea is cleaner and emptier — no off-notes, and no body either. It tastes thin and slightly hollow.

Sources