Weak has two meanings, and the fix differs.
Weak but balanced
The cup tastes correct — sweet, no sourness, no bitterness — just dilute.
That is a strength problem. Use more coffee, or less water. Move from 1:17 to 1:15.
Weak and sour
That is under-extraction, and adding more coffee makes it worse.
Grind finer. The main lever. Hotter water — 94 to 96 °C. Longer contact. A V60 that drains in 90 seconds is too fast; aim for 2:30 to 3:30 for a 15 g brew.
Check the obvious
Are you weighing? Scoops vary by 30% or more with grind size and bean density.
Is the water actually hot? A kettle poured into a cold carafe, into a cold dripper, over cold grounds loses several degrees before it touches coffee. Preheat everything.
Is the coffee stale? Old coffee gives thin, flat cups regardless of technique.
The pour
Water bypassing the bed is a common cause. Pouring onto the paper sends water straight down the wall without touching coffee. Keep the pour in the middle two-thirds.
A shallow bed in a big dripper channels. If you brew small amounts often, use a smaller dripper.
Water again
Distilled or heavily softened water cannot extract properly. If everything else is right and it is still thin, test the water.
Last reviewed 8 August 2026