Fertilizers, which are commonly used in agriculture and lawn/gardening, can lead to water pollution in a few key ways:

1. Nutrient runoff – Fertilizers containing nitrogen and phosphorus can be carried by rainwater and irrigation runoff into nearby rivers, lakes, and oceans. This excess of nutrients in water bodies can cause algal blooms, which deplete oxygen levels and harm aquatic ecosystems.

2. Leaching – Fertilizers that are not fully absorbed by plants can leach down through the soil, contaminating groundwater supplies that feed into larger water systems.

3. Sewage overflow – When wastewater treatment plants are overburdened, they may release untreated sewage containing residual fertilizers into waterways during heavy rain events.

4. Improper disposal – If excess fertilizers are improperly disposed of, such as pouring them down drains, the nutrients can end up polluting nearby water sources.