A B737-300 IN DSCNT AT 12000 FT HAS CAPT'S AIRSPD; ALTIMETER; VSI; SWEEP CLOCK QUIT AND A WINDSHIELD OVERHEAT HAPPEN AT THE SAME MOMENT. BURST WATER LINE CAUSED A FLOODED ELECTRICAL AND ELECTRONICS COMPARTMENT.

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AT APPROX 12;000 FT; CAPT'S AIRSPEED; ALTIMETER; VSI; SWEEP CLOCK ALL QUIT WORKING AT THE SAME MOMENT A WINDOW OVERHEAT HAPPENED. APPROX 5-10 MINS EARLIER; WE HAD THE FA'S SHUT OFF THE HANDLE UNDERNEATH THE SINK IN THE FORWARD LAVATORY DUE TO A RUNNING FAUCET THAT WOULDN'T SHUT OFF PER MAINT CTL INSTRUCTIONS. I ASSUMED CTL OF THE PLANE; AND LANDED IN VMC CONDITIONS WITH MY INSTRUMENTS WORKING EXCEPT INTERMITTENT GS/LOC FLAGS ON THE FO SIDE. AFTER THE FACT; AND AFTER TALKING WITH MECHANICS THE NEXT MORNING; OUR BEST GUESS IS THE FLT ATTENDANT INADVERTENTLY DIDN'T SHUT OFF THE HANDLE; BUT INSTEAD MOVED IT TO DRAIN. THIS CAUSED A BURST WATER LINE; THEN WATER GOT INTO THE E&E COMPARTMENT; THUS CAUSING THE INST PROBS. UPON POST FLT INSPECTION; WATER WAS VISIBLY AND NOTICEABLY COMING OUT JUST FORE AND AFT OF THE E&E COMPARTMENT. IT SHOULD BE NOTED THAT WHILE THIS PROC IS IN THE IRREGULAR OPS MANUAL; THE SHUT OFF VALVES ARE NOT IN ANY WAY LABELED WELL; AND ALL FLT ATTENDANT'S WE SPOKE TO SAID THEY'VE NEVER HAD RECURRENT TRAINING ON THIS PROC. WE LOOKED OURSELVES AND THERE IS NO PLACARD OR WARNING THAT WE COULD SEE. ALSO OF NOTE; WE COULD FIND NOWHERE IS THERE A PRECAUTION IN THE AOM; FOM; OR QRC FOR THIS PROC AND MAINT CTL OFFERED NO GUIDANCE AS A PRECAUTION. I HIGHLY RECOMMEND THIS PROC BE REVIEWED AND MUCH MORE READABLE; LARGE PLACARDS BE PUT ON THE VALVE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT WHEN THE E&E COMPARTMENT WAS OPENED; WATER POURED OUT LIKE A DAM BROKE. THE RPTR SAID ALL OF THE UNITS IN THE COMPARTMENT WERE REPLACED. THE RPTR STATED THE FLT OPS MANUAL DOES NOT REFER TO THE LAVATORY VALVES AND VALVE POSITIONS; AND NEITHER DOES THE CABIN ATTENDANT'S HANDBOOK GIVE ANY DESCRIPTION AND OPERATION OF THE VALVES. THE RPTR SAID THE CABIN ATTENDANTS ARE SHOWN THE VALVES AT INITIAL TRAINING AND NEVER RECEIVE ANY RECURRENT TRAINING AGAIN.