The　occurrence　and　distribution　of　antibiotic　resistance　genes　(ARGs)　in　drinking　water　treatment　plants　(DWTPs)　and　finished　water　are　not　well　understood,　and　even　less　is　known　about　the　contribution　of　each　treatment　process　to　resistance　gene　reduction.　The　prevalence　of　ten　commonly　detected　sulfonamide　and　tetracycline　resistance　genes,　namely,　sul　I,　sul　II,　tet(C),　tet(G),　tet(X),　tet(A),　tet(B),　tet(O),　tet(M)　and　tet(W)　as　well　as　165-rRNA　genes,　were　surveyed　in　seven　DWTPs　in　the　Yangtze　River　Delta,　China,　with　SYBR　Green　I-based　real-time　quantitative　polymerase　chain　reaction.　All　of　the　investigated　ARGs　were　detected　in　the　source　waters　of　the　seven　DWTPs,　and　sul　I,　sul　II,　tet(C)　and　tet(G)　were　the　four　most　abundant　ARGs.　Total　concentrations　of　ARGs　belonging　to　either　the　sulfonamide　or　tetracycline　resistance　gene　class　were　above　10(5)　copies/mL.　The　effects　of　a　treatment　process　on　ARG　removal　varied　depending　on　the　overall　treatment　scheme　of　the　DWTP.　With　combinations　of　the　treatment　procedures,　however,　the　copy　numbers　of　resistance　genes　were　reduced　effectively,　but　the　proportions　of　ARGs　to　bacteria　numbers　increased　in　several　cases.　Among　the　treatment　processes,　the　biological　treatment　tanks　might　serve　as　reservoirs　of　ARGs.　ARGs　were　found　in　finished　water　of　two　plants,　imposing　a　potential　risk　to　human　health.　The　results　presented　in　this　study　not　only　provide　information　for　the　management　of　antibiotics　and　ARGs　but　also　facilitate　improvement　of　drinking　water　quality.　(C)　2014　Elsevier　B.V.　All　rights　reserved.