Store whole watermelons in a cool place or refrigerate when possible
Refrigerate cut watermelon immediately
Consume cut pieces within a few days
How to Protect Yourself
A few simple precautions can reduce your risk of spoiled fruit:

Inspect before cutting: Avoid melons with soft spots, cracks, or damp areas.
Wash the rind: Rinse thoroughly under running water before slicing to prevent contamination.
Use clean tools: Always cut with a clean knife on a clean surface.
Check after cutting: Look, smell, and sample a small piece before eating