I looked into hard water when I first read the CG Handbook and realized pretty quickly I don't have it. The best indicator is whether or not you can get your soap to lather. Bad buildup (which I have yet to get) in the hair is also a good indicator of hard water. There was a water bottle test:

How to Determine if You Have Hard Water: 5 steps (with pictures)

There it is! Just in case it's to anyone's interest.

Jas, how much AVG to do mix with the FSG ratio wise? Should I just start out tossing a tsp into the container and giving it a swift stir?
3A - C, HP, ME, HD. (Coarse, High Porosity, Medium Elasticity, High Density.)

CG since Nov. 2012

Poos: SM Moisture Retention + Yucca Baobab, TJ's Tea Tree Tingle
Condish: TJ 'sTea Tree Tingle*, SM Moisture Retention* + Curl & Shine + Yucca Baobab, Yes to Blueberries
Stylers: KCKT*, SM Curl Enhancing Smoothie* + Curl & Style Milk*, KCCC*, FSG*, CJ Pattern Pusha, Curl Keeper
Sealers: Jojoba* or Grapeseed* oil

* = HG