Quick fixes by symptom

ProblemFirst changeThen check
Bitter or dryingShorter steepLower temperature, smaller dose, water chemistry
Weak or waterySlightly more leafCorrect volume, hotter water within range
Flat aromaFresh water and preheated vesselLeaf freshness, kettle cleanliness
Too smoky or roastedShorter, cooler steepWhether the flavor is intrinsic to the style
Musty, chemical, moldyStop and inspectPackaging, leaf condition, water, equipment

When should tea be discarded?

Do not drink tea with visible mold, pest damage, wet or compromised packaging, or a persistent foreign chemical or musty odor. Normal aging aromas vary by tea, but a calculator should not talk you into consuming questionable material.