Water: tap, filtered and bottled, same leaf
23 March 2025 · 2 min read
The tap water in this flat is hard, somewhere around 280 mg/l of dissolved solids by the figure on the supplier’s report, and it leaves a film on the inside of the kettle and a scum on black tea. I had been assuming it was also dulling the oolongs, so I tested that assumption with a lightly roasted rolled oolong, 6 g per 120 ml at 95 °C, three sessions on one afternoon, one with each water, washing the gaiwan between.
Tap water: the liquor was slightly darker than I expected, and the aroma off the lid was muted. In the mouth it was round and sweet but short; the finish disappeared within twenty seconds, and the floral notes I know this tea has were a rumour rather than a presence. Pleasant and dull. This is how I had been drinking it for a year without knowing.
Jug-filtered tap water: visibly paler liquor, and a clear lift in aroma, the floral top note arriving as soon as I lifted the lid. The finish lengthened to perhaps a minute. There was a touch more astringency, which I think is the real character of the tea coming through rather than a fault. This was the best cup of the three.
Bottled water, a soft one with about 30 mg/l of dissolved solids: the palest liquor by far, and the aroma was the strongest, almost perfumed. But the body was thin, watery in the middle of the mouth, and the astringency was sharper than in the filtered cup. It tasted like a diagram of the tea rather than the tea. I have read that very soft water lets everything out at once and gives the minerals nothing to bind to, and that is roughly what it felt like.
So the jug filter stays, and I will stop looking at the bottled water in the shop. For the record, the same test on a black tea the following week gave a less dramatic result: tap and filtered were close, with filtered a little brighter, and the soft bottled water again gave the thinnest cup. Hardness seems to hurt the delicate teas most, which is about what you would guess, but it was worth tasting rather than guessing.