Program Updates

Final Water Quality Tests

Posted Nov 30, 2015

My name is Kirsty Moriarty. I am a volunteer with Aguayuda. I have a degree in Microbiology. I am assisting the Aguayuda team with the water quality tests required to complete the Lazos de Agua project. I have been responsible for testing the water source and filtrate in 21 different communities for a variety of microbiological and chemical parameters. Every morning, I visit one to three communities with a member of the Aguayuda team to collect water samples. Depending on the community, I typically collect between three to five water samples per site. For communities with water filters I collect two pre-samples (one 100 mL sample and one for a 1:10 dilution for microbiological analysis) and three post samples (2x 100 mL samples for micro and 1 for chemical analysis). While in the field, I measure turbidity (the clarity of the water) and the presence of total dissolved solids (TDS; a measure of dissolved ions, salts, and metals). It is especially important to measure TDS while in the field because this chemical property has an inverse relationship with temperature—that is, as temperature increases, TDS decreases, and vice versa. Measuring in the field allows for a more accurate representation of the water quality in each community.
After I collect the samples, I return to the lab and begin my work. Microbiological samples are prepared using IDEXX Quanti-Tray 2000 and Colilert media and analyzed 24 hours after incubation at 35°C. This media detects both total coliforms and E. coli and measures their presence as most probable number (MPN/100 mL). Chemical and physical analyses are performed in accordance with Wagtech Potolab testing procedures. Depending on the number of samples collected, this process takes approximately three to five hours.

The results obtained so far have been quite promising. All of the communities are in line with the parameters outlined by the Lazos de Agua program for nitrates, arsenic, and fluoride concentrations as well as for E. coli. The major issue I can see in many communities is the salinity or the measure of TDS in the water. Of the communities I have tested thus far, 11 of the 21 have values above the threshold recommended by the program. Additionally, many communities have high levels of total coliforms in their source water. The measure of total coliforms in water, however, does not necessarily mean the water is fecally contaminated. Rather, total coliform measurement is used as an indicator or likelihood of fecal contamination. Overall, I believe the water solutions implemented by Aguayuda in the respective communities have had a very positive effect on the health of the people of La Guajira.

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