{TAIL ~ The O ring} prevents {HEAD ~ water} from otherwise flowing through the channel and externally of the water filtration system 
{ TAIL ~ The O ring } prevents { HEAD ~ water } from otherwise flowing through the channel and externally of the water filtration system
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH