An interesting conversation with a water district QA person

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trentm

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Recently, I had the opportunity to collaborate with a brewery in Monterey CA on a GABF Pro-Am competition beer. The brewery does not treat their water other than carbon filtering. Naturally I wanted to try to understand the water profile we were using so I went online to look at the city water report (see first image below).

Not terrible looking at the average but the range was reason for concern. So I contacted the water district and finally got through to the QA person to ask if I could get the most current analysis. She was very knowledgeable and willing to help but she informed me that a current analysis would do me no good. She then explained that the city receives water from 4 different sources including 3 wells and a desalination plant. A water sample is taken each time a new source is brought online but before blending with what is still in holding. So a sample in Monterey is never reflective of what is actually coming out of the tap. We decided have the actual water from the brewery tested post filter (see second image below).

I just wanted to put this out for those using city water reports from districts that use multiple sources. But also take this for what its worth as this is CA where regardless of the current drought, "whiskey's for drinkin and water's for fighting over." Other districts may not use this testing protocol.

By the way: the desal plant is desalinating well water that has had sea water encroachment due to excessive irrigation in the Salinas Valley and lack of rainfall which replenishes the aquifer. But hey, everybody wants fresh lettuce!

Water Report Monterey pic.png


Alverado water.png
 
Within limits. Looking at his chloride: range 16 - 199 (average 92) at the feed would, in a system with 95% rejection, translate to 0.8 - 10 (average 4.6) in the permeate. Chloride of 10 can be appreciable when compared to 0.8. Now these are, of course, the extremes. The standard deviations would be of interest but water reports seldom give that. Note that the coefficients of variation are the same (assuming the rejection remains constant) in feed and permeate.
 
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