We don't have synonyms for back-water yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are backwater, back water and blackwater.
(n) :
Alternative form of backwater: the water held back by a dam or other obstruction [The water held back by a dam or other obstruction.]
(n) :
Alternative form of backwater: water used in the papermaking process. Recycled to reduce usage of fresh water, and usually containing residual amounts of chemicals and fibres. [The water held back by a dam or other obstruction.]
(n) :
Alternative form of backwater: the water held back by a dam or other obstruction [The water held back by a dam or other obstruction.]
(n) :
Alternative form of backwater: water used in the papermaking process. Recycled to reduce usage of fresh water, and usually containing residual amounts of chemicals and fibres. [The water held back by a dam or other obstruction.]