The water left over after boiling eggs can be surprisingly useful because it contains nutrients that leach out of the eggshells during the boiling process.
Eggshells are made primarily of calcium carbonate, and when boiled, a small amount of this mineral dissolves into the water. This calcium-enriched water can be beneficial for plants that thrive in slightly alkaline soil and need extra calcium for healthy growth.
Along with calcium, the water may also contain trace amounts of phosphorus and magnesium from the eggshells, which can further nourish the plants.
Plant fertilizer: Let the water cool completely then use it to water plants. Avoid using it on plants that prefer acidic soil, such as blueberries or azaleas.
Composting Boost: Add cold water to your compost bin to add extra minerals.
Clean: The calcium in the water can help soften stubborn stains on surfaces or pots.
Caution:
Salt water: If you add salt to boiling water, do not use it on plants, as the salt can damage them.
Cool first: Always let water cool to room temperature before using it, as hot water is harmful to plants.
