Most people don't know if their water or soil contains dangerous 'forever chemicals'. A mapping tool would aggregate existing data into an easy-to-use interface.
Build a web app that visualizes known contamination sites and estimates risk for other areas based on proximity.
Monetize through partnerships with water testing services and premium reports for homeowners.
Start with a simple map overlay of known EPA data, then add more sources.
The risk is incomplete data making the tool unreliable.