Nitrite Levels in Reverse Osmosis Water

Root Causes
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Does anyone have a good reference discussing the nitrite levels in reverse osmosis water? It seems RO will reduce nitrite levels, but can a reasonable assumption be made? This paper (https://pubs.acs.org/doi/10.1021/acs.oprd.0c00224) makes some estimates, but I wonder how valid this is to use for general estimates of nitrite levels when not data is available.

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Long story, but I worked for a company in the water purification space for a short minute. Between pressure regulation and the membrane itself, you cannot just say that you’re using RO & have perfect water. Without data, including conductivity or resistivity after the membrane, all you can say is that the water coming out should be better than the water that went in. You cannot say that it is fit for purpose.

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Thanks for your response! I should have mentioned that the post-RO water meets USP <1231> and the final conductivity is ≤1.3 μS/cm at 25°C. However, nitrates and nitrites are not tested. I’m wondering if some worst-case scenario calculations be performed to determine possible nitrite levels.

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RO does not guarantee nitrosamine free water-there is evidence published regarding NDMA azeotrope so distillation is not a guarantee and there is a publication about RO and nitrosamines showing a different efficiency of removal but for simple nitrosamines the efficiency is low

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RO will reduce the nitrite concentration from incoming feedwater, like it does all other ions. But the degree of removal, call the rejection efficiency, does vary from ion to ion. A typical, well-maintained RO system will reject 95-ish% of the ions, sometimes more, sometimes less. The most knowledgeable folks I know are those that build and design water systems, like a Veolia, BWT, Evoqua, etc… as well as RO manufacturers and many other companies. They have the models to predict rejection efficiency for individual ions, and it is backed by their own in-house data. It does exist for the most common ions, Na+, chloride, sulfate, bicarbonate… maybe they have for nitrite too?

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