All Rainbow vacuum systems use a water pan. That is what separates it from a traditional vacuum. From 1955 to current production there are only three different water pans.
If you want to upgrade to a larger 4 quart water pan, it again only a choice between three versions.
Item #:R6854This standard 2-quart Water Basin fits the D4C, D3C, and D3A models and is used to replace a Water Pan which has become cracked or worn.Regular: $44.80 USD
Online: $38.40 USD
Item #:R2823This larger, four-quart Water Basin (Pan) for the D4C, D3C, and D3A model Rainbow. Quickly tackle heavy-duty jobs while changing the water less often.Price: $50.16 USD
Item #:R10236Your Rainbow is useless without the Water Basin (Pan). Here is a 2.5 quart original factory replacement for all e2 and E-2 (e SERIES™) model...Regular: $41.65 USD
Online: $35.30 USD
Item #:R7895The four-quart Water Basin (Pan) has many advantages. Tackle heavier-duty jobs more efficiently. For all e2 and E-2 (e SERIES™) EXCEPT the Black...Regular: $54.59 USD
Online: $47.18 USD
Item #:R14325This four quart Water Basin fits your e2 Black (E2 Type 12) with the R14002 dolly assembly. DOES NOT fit any other model.Regular: $46.68 USD
Online: $39.36 USD
Item #:R601This standard 2-quart water basin fits the D2A, D2, and D model Rainbow. DOES NOT FIT any other model.Price: $77.53 USD
Item #:R10851BLHas your water basin for your RainMate become damaged? Purchase this factory replacement today.Price: $23.73 USD