“What’s in the well comes up in the bucket” is a metaphor meaning that what’s in someone’s heart will come out of the mouth. “What is in the well will be in the bucket; what is in the warehouse will be in the shop” was cited in print in 1833. There appears to be a large time gap until the 1990s, when the saying became popular again in print.
 
The saying is sometimes attributed to a farmer from Tennessee or from Texas, but the saying cannot be traced to any specific state.
 
   
Google Books
Morning Exercises for the Closet for Every Day in the Year.
By William Jay
Baltimore, MD: Plaskitt & Co. and Armstrong & Plaskitt
1833
Pg. 233, col. 1:
What is in the well will be in the bucket; what is in the warehouse will be in the shop.
 
Google Books
Thriving as a Working Woman
By Gwen Ellis
Wheaton, IL: Tyndale House Publishers
1995
Pg. 199:
Harold Lindsell, a well-known Christian writer and publisher, once said, “What’s in the well comes up in the bucket.” You can’t draw water from an empty well.
 
Google Books
Colossians and Philemon
By David E. Garland
Grand Rapids, MI: Zondervan
2009
Pg. ?:
A Tennessee farmer once said, “What comes up in the bucket is usually what’s down in the well.”
 
OCLC WorldCat record
What’s in the Well Comes Up in the Bucket.
Author: Locy, Charles
Publisher: Aviva Pub 2011.
Edition/Format: Book : English
 
Google Books
Praying for Your Job:
Prosperity, Fulfillment, Happiness
By Elmer Towns and David Earley
Shippensburg, PA: Destiny Image Publishers, Inc.
2011
Pg. ?:
The old farmer said, “What’s in the well, comes up in the bucket,” so what is in the heart will come out of the mouth.
 
Twitter
George_Cotter‏
@pistolero_padre  
@CyndiLuvsGod Old Texas saying: What’s in the well is what comes up in the bucket. Related to spiritual conflict between the flesh & spirit
7:39 AM - 15 Aug 12