Do large aircraft accumulate water in their tanks?
AFAIK all aircrafts accumulate water in their tanks. Since you ask for large aircraft acccording to wikipeadia:

FAA definition of large aircraft


  The US Federal Aviation Administration defines a large aircraft as any
  aircraft with a certificated maximum takeoff weight of more than
  12,500 lb (5,700 kg)


EASA definition of large aircraft 


  The European Aviation Safety Agency (EASA) defines a large aircraft as
  either "an aeroplane with a maximum take-off mass of more than 5,700
  kilograms (12,600 pounds) or a multi-engined helicopter."


Here is Airbus A340 draining process with explanations on youtube 
                
            

Here you can find EASA regulations about draining https://www.easa.europa.eu/download/etso/ETSO-C76b_CS-ETSO_11.pdf

Here is FAA regulations about water draining
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-125.pdf

On FAA AC 20-125 p.7 states


  WATER REMOVAL/PREVENTION. Water is best removed from jet fuel by
  passing the through approved filtration/separation equipment. A
  two-hour settling period and the use of floating suction to drain fuel
  from the top of a storage tank are also recommended to help prevent
  water from being introduced into a fuel system. Water will readily
  settle-out of aviation gasoline; therefore, filters/separators are not
  required for water removal, however, they are necessary for removal of
  solids. The best means to minimize the amount of water entering a fuel
  system is the inspection and proper maintenance of equipment and the
  training of ground and flight personnel.


Also FAA AC 20-125, Water In Aviation Fuels, para 7 c suggests that it may be necessary to gently rock the wings of some aircraft while draining the sump in order to completely drain all the water.