As in every profession, the water tasters who work for the Metropolitan Water District have their own lexicon. Here are some tasters' terms for problem water.
Cardboard or rubber: Cause unknown, but chlorine rids the water of the taste.
Grassy: Caused by hexenol, nicknamed leaf alcohol, which occurs in all green plants
Musty-moldy: Caused by 2-methylisoborneol, an algae byproduct every fall and summer. People can taste 5 parts per trillion.
Swampy: Caused by dimethyltrisulfide at certain concentrations, which smell like garlic or onions and result from a breakdown of proteins of algae.
Swimming pool: Caused by bichloramine, same cause as above.
Watermelon, melon or cucumber: Caused by nonenalfrom from algae.
Dry mouth: Water high in dissolved solids and minerals.
Fishy: Water with a rotten, fishy smell caused by trimethylamine, a breakdown of algae proteins.
Geranium: Water with trichloramine, occasional byproduct from mixing of chlorine and ammonia to treat water.