Boiled foods release nutrients of one kind or another, so why pour their cooking water down the drain? Let the water cool, and then use it to give a garden plant or two a healthful drink. But take note: When you cook any of the following, do not add salt to the water because salt is harmful to plants.
Eggs. Hardboiled eggs leave calcium in the cooking water, so use the liquid to water calcium-loving solanaceous garden plants: tomatoes, potatoes, eggplants, peppers, chayote squash, tomatillos.
Spinach. Plants need iron, too — and spinach water gives them not only iron but also a decent dose of potassium.
Pasta. Starchy water will spur the release of plant nutrients in the soil, meaning starch may be better for plants than for you.