I filtered my water and the tea got worse

In short

Filtering is usually an improvement and it can be taken too far. Tea needs some dissolved mineral to extract properly and to carry body; water stripped of everything produces a clean, characterless cup, and this is the one water problem that gets worse the harder you work at it.

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. Distilled or reverse-osmosis water with nothing dissolved in it

   Water chemistry

   Check: Is the water distilled, RO, or from a strong multi-stage filter?

   Fix: Move back to filtered tap water, or cut RO water with some tap water. A moderate mineral content extracts more and carries more body than pure water does.

2. 2. An ion-exchange jug used in a soft-water area

   Water chemistryInferred by TeaHQ, not established

   Check: Was your tap water already soft before you started filtering?

   Fix: In a soft-water area a carbon-only filter is usually enough — it removes chlorine compounds without lowering hardness any further. The hardness reduction is only useful where there is hardness to reduce.

3. 3. The problem was chlorine, and it has already been solved

   Water chemistryInferred by TeaHQ, not established

   Check: Did the tea improve at first and then start tasting empty as you filtered more aggressively?

   Fix: Stop at the level that removed the off-note. Chlorine removal and mineral removal are separate jobs, and only the first was ever needed.

4. 4. The dose is now wrong for a more efficient extraction

   Leaf quantityInferred by TeaHQ, not established

   Check: Have you adjusted the leaf since changing water?

   Fix: Add ten to twenty per cent more leaf and taste again. Different water extracts differently, and the parameters that suited the old supply are not automatically right for the new one.

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.
• Gongfu brewing (gaiwan) — A high-leaf, low-volume, many-infusions approach: a great deal of leaf in a small vessel, steeped for seconds at a time and poured off completely, repeatedly.

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.
• The tea I loved in the shop is disappointing at home — A tea that was remarkable when it was tasted in the shop is ordinary in your own kitchen, from the same packet, within days of buying it.
• 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 cannot taste the difference between my expensive tea and my cheap one — Two teas at very different prices taste much the same in the cup, and the tasting notes on both packets describe things you cannot find.
• My white tea tastes of almost nothing — The cup is pale and barely flavoured, and it stays that way whatever is adjusted.

Sources