washed vs water-washed

washed and water-washed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
washed	No	Yes	No	No
water-washed	No	Yes	No	No

As adjectives, washed and water-washed are synonyms defined as:

washed (adjective)	water-washed (adjective)
clean by virtue of having been washed in water	clean by virtue of having been washed in water
wet as from washing; sometimes used in combination	washed or swept with water especially waves of the sea