Setting limit for Nitrite and Nitrate in water used for Active Ingredients synthesis

How to properly set a limit for Nitrite and Nitrate in potable and purified water used in a multipurpose plant for the manufacturing of the APIs?
We receive such request from EU Auhtority on a specific API, however a general limit seems more reasonable that a specific one being a multiporpose plant.
All the possibile NAMs should than take into consideration? If yes, the most known potent NAM (8 ng/day) should be used for set NAMs limit and convert for nitrite and nitrate? Is there any exception that can apply?

Interesting question here. I would limit the nitrite into the Acceptable intake of your more stringent NDSRI or nitrosamine in ppm (so the maximun daily dose enters into the equation) for purified water and looking if actually is realistically possible taking into account what is the actual value.

For potable water, that depends on the source, difficult to control it, without actually “purifying” it in our facilities.

Rather than looking to set limits I would first encourage you to read the Ashworth et al paper - in all be exceptional cases the standard applied for USP grade water should suffice.

Potential for the Formation of N-Nitrosamines during the Manufacture of Active Pharmaceutical Ingredients: An Assessment of the Risk Posed by Trace Nitrite in Water | Organic Process Research & Development (