s ▁were ▁built ▁on ▁either ▁side ▁of ▁the ▁river , ▁and ▁a ▁tunnel ▁was ▁constructed ▁between ▁them . ▁The ▁water ▁main ▁is ▁formed ▁of ▁tw in ▁steel ▁tub es ▁within ▁the ▁tunnel . ▁The ▁engines ▁were ▁normally ▁worked ▁in ▁pairs , ▁and ▁a ▁pair ▁could ▁deliver ▁ ▁per ▁day . ▁In ▁August ▁ 1 9 2 7 , ▁water ▁from ▁the ▁Ch el mer ▁started ▁to ▁be ▁used , ▁and ▁between ▁then ▁and ▁ 1 9 4 5 , ▁ 9 6 ▁per ▁cent ▁of ▁the ▁water ▁supplied ▁by ▁South end ▁Water works ▁came ▁from ▁Lang ford . ▁The ▁well s ▁and ▁bore hol es ▁were ▁maintained , ▁to ▁provide ▁a ▁backup ▁supply ▁when ▁necessary . ▁ ▁In ▁ 1 9 6 0 , ▁work ▁began ▁on ▁replacing ▁the ▁steam ▁engines ▁at ▁Lang ford ▁p ump ing ▁station ▁with ▁semi - autom atic ▁electric ▁p umps . ▁The ▁project ▁cost ▁£ 2 6 0 , 0 0 0 , ▁and ▁was ▁formally ▁inaugur ated ▁on ▁ 3 1 ▁October ▁ 1 9 6 3 , ▁when ▁Sir ▁George ▁Chap lin , ▁the ▁Chair man ▁of ▁Es sex ▁County ▁Council ▁switched ▁on ▁the ▁new ▁p umps . ▁In ▁the ▁late ▁ 1 9 6 0 s , ▁construction ▁of ▁a ▁new ▁treatment ▁works ▁next ▁to ▁the ▁storage ▁res er voir s ▁began . ▁The ▁works ▁cost ▁£ 1 . 5 ▁million , ▁and ▁were ▁opened ▁on ▁ 3 0 ▁June ▁ 1 9 7 0 . ▁They ▁can ▁produce ▁ ▁of ▁treated ▁water ▁per