When you boil an egg, some of the calcium from the shell leaches into the water. This is a good thing! You now have water plus calcium. Here are two good uses for the calcium water left over from cooking eggs.
- When the water cools down, use it to water tomatoes. It will add some calcium to the soil which can help prevent or treat blossom-end rot. (Add crushed up egg shells for more effect.)
- Use the water in making soups and stock. The calcium survived being boiled out of the egg shell, it will survive a little soup-making.