water boy

noun

a person who carries a canteen or bucket of drinking water to those too occupied to fetch it, as to soldiers, laborers, or football players.
a person who sees that livestock is supplied with water, as by filling water troughs.

Origin of water boy

First recorded in 1630–40

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

You brought my water-boy back with you last night, didn't you, Mr. Ballard?
The King of Arcadia
Francis Lynde
From boss to water-boy we were failures all; so we understood each other.
The Precipice
Elia Wilkinson Peattie
I'll help pass a law making it illegal for Hans Wagner to hang around a ball park except as water-boy.
At Good Old Siwash
George Fitch
On his plantation Henson served as water-boy, butler and finally as a field hand, experiencing the usual hardship of the slave.
The Journal of Negro History, Volume 3, 1918
Various
The water-boy was humped over the horn of his saddle as if he had found a stomach-ache in the breathless gallop.
The King of Arcadia
Francis Lynde