Harford County Household Hazardous Waste Collection Dates Havre de GraceHarford County Household Hazardous Waste Collection Dates Household Hazardous Waste (HHW) collection events are scheduled for the following dates: Saturday, November 11, 2023 Tuesday, February 6, 2024 Saturday, May 11, 2024 Details: https://www.harfordcountymd.gov/276/Household-Hazardous-Waste