The following are what I consider to be essential books on watercolor:
The Watercolorist's Essential Notebook by Gordon MacKenzie
This beautifully illustrated book is absolutely full to bursting with solid information about watercolor tools, painting techniques, and compositional tricks of the trade. Every time I open this book I learn something new and in fact, because there is so much information in this book, it is indeed best absorbed in small increments.
The Complete Guide to Watercolor by Ray Smith & Elizabeth Jane Lloyd
This is another information-heavy tome on watercolor with detailed chapters on Materials, Techniques, Color, Landscapes, and Still Life. This is also a book best consumed bit by bit as the amount of information within can be overwhelming if taken cover to cover.
Water Paper Paint by Heather Smith Jones
This book presents 30 exercises in watercolor designed to teach basic techniques (such as brush handling) and to encourage playful exploration of the medium. This is a book worth going through page by page, project by project. This is a great book for beginning to intermediate painters.
A Passion for Watercolor: Painting the Inner Experience by Stefan Draughon
Many, many watercolor technique books will teach you, step-by-step, how to paint a specific scene or object and I'm not fond of that approach. This book appeals to my desire to explore watercolor more randomly, learning by doing. It is not a book for technical information about the medium but rather an idea book for subjects to explore in watercolor and ways to approach those subjects. I'd say this is a book for people already familiar and comfortable with watercolor and who want to take their work to the next level.
A Couple of Notes: All links in this post are affliate links which means that if you click on and purchase any of these books through this blog, a bit of change drops into my bank via Amazon.
Additionally, Watercolor Wednesday will be taking a short break so I can generate new material and posts. As always, if you have any questions about watercolor you'd like to see addressed, please send them to me at firstname.lastname@example.org and I'll do my best to answer your inquiries.