That is what you have to validate it is just important that the TOC unit it set to have temperature compensations you have to ensure that the other points do not have any dead legs at the sampling points and that you have a set procedure of how you sample . if you have say 3 months parallel testing you can motivate to reduce sampling it would be ideal to have continuous recording so you can monitor if some thing changes you revert back to full sampling , be aware that samples should tested ASAP as if they stand around they will absorb CO2 Hans
There are no guidances (as I recall). As I recall (it’s been ~40 years since I was QC Manager) we had the online TOC meter in the lab which was the end of the loop, but each POU (point of use) must be validated before the water distribution system comes into use. Biofilms can appear anywhere (thus eliminating downspouts) so placement of the TOC meter is not significant. You must have an weekly monitoring program as well.