Take a closer look to this: ...
Published by Robert Stevens, Snr. Business & Appl. Development Mng. EU for Industry
Take a closer look to this: https://www.epa.gov/dwstandardsregulations
NOM is know giving molt smell to water, and TOC is a good precursor - being an objective measurement - rather than an subjective tasting.
Secondarily TOC is also measuring the sum of all carbon species - from e.g. dead-/living organisms, as well as from chemical compounds - and thus could be very actively be used to determine is potable and/or bottled water is safe to drink. Therefore the (US)EPA is obliging TOC as a standard measurement technology for safety & health reasons too!
You can also find a lot on what our company Hach can provide you with to control water quality, such as i.e. TOC under: www.Hach.com
Best of luck!