Threats　from　landfill　leachate　leakage　to　groundwater　quality　in　remote　areas　is　a　major　concern　globally.　Buffering　distance　(BFD)　maintained　between　landfill　site　and　groundwater　supply　wells　is　important　to　prevent　drinking　water　from　contamination　of　hazardous　pollutant.　Ignoring　the　leakage　increase　in　the　end　of　landfill　life　leads　to　an　underestimate　of　BFD　demand,　posing　potential　threat　to　drinking　safety.　This　paper　constructs　a　framework　for　BFD　prediction　with　the　consideration　of　landfill　performance　degradation　by　coupling　landfill　performance　evaluation　model　with　the　aging　and　defect　evolution　model　of　landfill　engineering　materials,　and　carries　out　model　application　and　verification　in　a　coastal　hazardous　waste　landfill.　The　results　show　that　during　the　life　cycle　of　a　landfill,　its　BFD　experienced　a　1.5-time　increase　from　the　start　of　its　operation　to　its　life　end　and　reached　3000　m.　Under　the　condition　of　landfill　performance　degradation,　the　BFDs　required　to　attenuate　heavy　metals　experience　more　increase　than　those　of　organic　pollutants;　BFD　required　for　zinc　(Zn),　for　example,　increases　720　m　over　the　no-degradation　condition,　while　2,4-dichlorophenol(2,4-D)　increases　by　only　288　m.　Considering　the　uncertainty　sourced　from　model　parameter　and　structure,　the　BFD　should　be　more　than　4050　m　to　ensure　long-term　safe　drinking　under　unfavorable　conditions　such　as　large　amount　of　leachate,　weak　degradation　and　fast　diffusion　of　pollutant　in　vadose　and　aquifer.　If　the　BFD　cannot　meet　the　demand　at　the　end　of　the　landfill　life,　the　leaching　behavior　of　solid　waste　can　be　controlled　to　reduce　it　depending　on　BFD.　For　example,　when　the　leaching　concentration　of　Cd　in　the　waste　is　reduced　from　0.6　mg/L　to　0.17　mg/L,　the　buffering　distance　is　be　reduced　from　3000　m　to　500　m.