Qantas had a similar issue several years back, though there was no flight control restriction as regards hand flying it.
The ATSB report.
They flooded the galley, water dripped onto 3 of the 4 Generator Control Units, AC busses 1,2+3, AP, AT, wx radar & the Effo's screens were lost. The cause was found to be a failed drain line heater that allowed ice formation and subsequent backing up of waste water which then flowed through a split in the drain line, onto inadequate drip shields over the E&E bay and finally into the avionics.