The opposite of "influent" is "effluent." Influent refers to water flowing into a system, while effluent refers to water flowing out of a system.

Water coming in.

An effluent stream receives water from the banks surrounding it and so gets bigger as it goes along.

An influent stream donates water to the banks around it and so gets smaller as it goes along (think desert conditions)

Yes very much so because children want to be like their parents when they grow up

affluent - sea water

effluent - river water (the flow out of sea)

influent - river water (the flow into sea)