Organic content in water can be measured by COD (chemical oxygen demand) or BOD (biochemical oxygen demand.) The challenge is that these are specialized tests that measure reactions. For example, the BOD test is generally a 5-day process. There isn’t yet a simple probe, like a resistivity or conductivity meter, for accurate organic measurement. So, the practical solution is to use a large granular activated carbon (GAC) tank and change it out on a conservative frequency.