this week in our "global ideas" series, our reporter thomas hasel visited some informal settlements thathome to residents of the kenyan capital, nairobi. they're taking water cleanup into their own hands. reporter: frfreeing the nanaii river fromom garbage migight m like a never-endining battle.. the name nairobi c com from kenya's ssai tribe, and means "cooool and refrfreshing wate" but ththese days, ththe cool ws are lilittered with h refus. concerned d residents frfrom e nearby slulum no longer r wano accept thehe environmental didisasterightht at eir doororstep dia: whehewe were young, this river r wasn't as didirty. so we decideded tolean i it. in the pasast, we went swimmingn the ririver. but that's's not possiblble any, becaususe the water r qualitys chananged. we want to t try to returnrn io the y y it ud to b be. reporter: lydia wamboi is e e of out t 70 residentsts of the korogocho o slum in eaststen nairobi who o works with t the organization komb grnn solulution they've e dedicated ththemselvo prototecting the e environment.. wawamboi knows t that the polln in t r river is no