Performed inspection of leak located under kitchen sink and found leak was coming from a PEX coupling. Removed damaged section and plumbed in new section with half inch PEX and fittings. After inspecting the existing red PEX that was leaking it appeared the PEX was beginning to fail and could lead to more leaks in the future. Customer also had water damage and mold to drywall and surrounding cabinets. Recommended performing proper mold mitigation