From Longman Dictionary of Contemporary Englishrainwaterrain‧wa‧ter /ˈreɪnwɔːtə $ -wɒːtər, -wɑː-/ noun [uncountable] DNwater that has fallen as rain
Examples from the Corpus
rainwater• Luckily their cargo included rice which they supplemented by catching fish and collecting rainwater.• By collecting rainwater, you can avoid using city water, which can sometimes brown the edges of the foliage.• A decrease in acidity of rainwater was recorded at nine sites, with only one recording a statistically significant increase.• The cup of the flower was full of rainwater.• Two buckets hanging on the stern gathered a couple of inches of rainwater in a few moments.• And sand will provide a stable base providing rainwater can not reach it.• Like the rainwater they'd drunk, little green guy meat seemed harmless.• But most of the flooding was caused by creeks and streams filled with rainwater. 