Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Runoff water is wasted water. 
Sentence2: Streams may start with wasted water.
wasted

Sentence1: Enveloped viruses make their own membranes. 
Sentence2: Some viruses make their own membranes.
make

Sentence1: treating water is used to remove harmful substances before drinking. 
Sentence2: treating water is used to remove harmful substances before hydration.

harmful