▁such ▁as ▁a ▁pipe , ▁d itch , ▁ship ▁or ▁factory ▁sm ok est ack ." ▁Therefore , ▁among ▁the ▁most ▁common ▁examples ▁of ▁point ▁source ▁poll ution , ▁poor ▁factory ▁and ▁se w age ▁treatment ▁appear ▁high ▁on ▁the ▁list ; ▁although ▁not ▁as ▁frequent , ▁but , ▁never theless , ▁equally — if ▁not ▁more — d anger ous , ▁oil ▁sp ills ▁are ▁another ▁famous ▁example ▁of ▁point ▁source ▁of ▁poll ution . ▁On ▁the ▁other ▁hand , ▁non - point ▁sources ▁of ▁poll ution ▁are ▁those ▁that ▁may ▁come ▁from ▁different ▁sources , ▁among ▁which , ▁poor ▁and ▁badly ▁monitor ed ▁agricult ural ▁activities ▁can ▁neg atively ▁affect ▁the ▁quality ▁of ▁any ▁nearby ▁sources ▁of ▁water . ▁ ▁Point ▁sources ▁of ▁poll ution ▁▁ ▁Indust rial ▁products ▁and ▁was tes : ▁Many ▁harm ful ▁chemical s ▁are ▁used ▁widely ▁in ▁local ▁business ▁and ▁industry . ▁These ▁can ▁become ▁drink ing ▁water ▁poll ut ants ▁if ▁not ▁well ▁managed . ▁The ▁most ▁common ▁sources ▁of ▁such ▁problems ▁are : ▁ ▁Local ▁business es : ▁Fact ories , ▁industrial ▁plants , ▁and ▁even ▁small ▁business es ▁such ▁as ▁gas ▁stations ▁and ▁dry ▁clean ers ▁handle ▁a ▁variety ▁of ▁ha z ard ous ▁chemical s ▁that ▁need ▁careful ▁management . ▁Sp ills ▁and ▁impro per ▁dispos al ▁of ▁these ▁chemical s ▁or ▁of ▁industrial ▁was tes ▁can ▁threaten ▁ground ▁water ▁supplies . ▁ ▁Le aking ▁under ground ▁t anks ▁and ▁pip ing : ▁Pet role um ▁products , ▁chemical s , ▁and