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Water treatment
Water treatment
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Would you suggest field blank/duplicate sample for CBTs?

During the Network's last webinar “Water quality testing in action: Making your testing program work in the real world” there were some questions to our panelist Dr. Anna Murray that couldn't been answered because of time constraints. She answered them in written for us to share with all of you. ¡Thank you Anna! 

If you missed the event, you can register to watch the recording here.

Question: Would you suggest field blank/duplicate sample for CBTs?

Yes, I suggest using quality control measures with compartment bag tests (CBTs). Field blanks are always useful to test for sources of contamination during sample collection and transport. Field duplicates are also helpful, but the interpretation of them can be difficult due to the semi-quantitative nature of the test. It is possible to do the duplicate comparison by checking for both samples landing within the same diarrheal disease risk category (<1, 1-10, 10-100, >100 MPN/100mL)

For quality control measures, after how many samples should you test a blank or duplicate sample, if you are testing many samples?

During the Network's last webinar “Water quality testing in action: Making your testing program work in the real world” there were some questions to our panelist Dr. Anna Murray that couldn't been answered because of time constraints. She answered them in written for us to share with all of you. ¡Thank you Anna! 

If you missed the event, you can register to watch the recording here.

Question: For quality control measures, after how many samples should you test a blank or duplicate sample, if you are testing many samples?

The decision may come down to time or resources, but with field lab tests, I have used 1 blank per every 20 samples run. (If there are fewer than 20 samples, the minimum would be one at the end of the run of samples. Even better is to do one at the beginning, one at the middle, and one at the end. For field blank samples collected in the field, I would include a minimum of one field blank per team member per week.  

What is the difference between water quality standards and water quality guidelines?

During the Network's last webinar “Water quality testing in action: Making your testing program work in the real world” there were some questions to our panelist Dr. Anna Murray that couldn't been answered because of time constraints. We are answering them here.

If you missed the event, you can register to watch the recording here.

Question: What is the difference between water quality standards and water quality guidelines?

The World Health Organization (WHO) is part of the United Nations (UN) and it focuses on international public health. The WHO writes the Guidelines for Drinking Water Quality (2011) to protect public health and help make sure that people are drinking safe water around the world.

The WHO Guidelines explain that safe drinking water will not make people sick at any time throughout their life, including when they are young, old or already sick. Safe drinking water should be good to use for all of our personal needs, including drinking, cooking and washing. The WHO Guidelines cover microbiological, chemical and physical parameters. However, it is stressed that microbiological quality is the most important since fecal contamination from people and animals is the biggest cause of illness and death around the world.

Countries need to adapt the WHO Guidelines for Drinking Water Quality to their context and realities; therefore, national standards vary among countries.

There is no single approach that is used worldwide. The Guidelines are recommendations to work towards, and they are not mandatory limits. Countries can take the WHO Guidelines... (More)

Quality control measure is interesting. Does it mean testing the reagents and testing methods, as well?

During the Network's last webinar “Water quality testing in action: Making your testing program work in the real world” there were some questions to our panelist Dr. Anna Murray that couldn't been answered because of time constraints. She answered them in written for us to share with all of you. ¡Thank you Anna! 

If you missed the event, you can register to watch the recording here.

Question: Quality control measure is interesting.  Does it mean testing the reagents and testing methods, as well?

Quality control methods can span a wide variety of checks to ensure the quality of your test methods (microbiological methods, chemical methods, or other methods). The ones I presented in the webinar are the basic quality control checks that are typical of field data collection. In laboratory analyses similar methods are used – namely blank samples and duplicate samples. Some additional control samples are also sometimes used, including “positive control” tests, where you test a sample that you know has a certain positive occurrence of the parameter you are testing, or “spiked sample” which has a high concentration of the parameter. These checks will give you a sense of how your procedure is performing. Then if there are issues identified, you can use that indication to investigate the root cause of the problem (protocol, human error, reagents, etc).