TC reported the water tank for the A side wiper is leaking. Picture send to OCC. ~~~~~ 3620 TC reported the A/S wiper water tank is leaking. Picture send to OCC. CE checked & found 3620 A/S wiper water leaking.  3620 Checked water level in wiper water tank ok, no leak from water tank. Wiper water pipe to turning knob checked ok, no leakage. Found water leak from detrainment door when performing water leak test by spraying water on detrainment ramp. Repatched & repaired ageing rubber gasket. Water leak test pass. No more water seepage.  Sarma/Alan/Lee PT/Kamarul/Anand/Shafie 45298