The song title is "Whitchi-tai-to". The original version is from the group EVERYTHING IS EVERYTHING (album name is the same), and the song was written by the group's sax player, Jim Pepper. He was part Creek and part Kaw, and the chanted lyrics come from a Peyote Chant of the Native American Church; the chant is about water. Jim Pepper later recorded a somewhat different version of the song on his own album "JIM PEPPER'S POW-WOW".

The song was covered by Brewer and Shipley, who used slightly different lyrics in the English part.

English lyrics (Jim Pepper's original version):
Water spirit feelings springin' round my head
Makes me feel glad that I'm not dead

The Indian lyrics, I can't be sure of. I don't speak the language, so I'd be trasncribing it phonetically. Most of what's been posted here is pretty close to what I hear:
Witchi tai tai himi ra
hora niko hora niko
he ne he ne no wa