The shells, which are rich in calcium, leach this valuable mineral into the water -- creating a nutritious tea that we've been wasting for as long as we've been gardening.
Basically, any water used to cook anything has a use. Starchy water from boiling rice or pasta or potatoes can be used to make breads or thicken soups. Vitamin-rich water from steaming or blanching vegetables is great for compost or soup stock. Now, we know to save egg-boiling water.
It's our everyday brush with chemistry.
These minerals and compounds interact with the water molecules and hitch a ride away from where they started. By reusing this enriched liquid elsewhere, we're just playing travel agent and directing them toward a more beneficial destination.
It has to be more fun than a trip through the sewer system!