Updating the water quality criteria for well and spring water used for potabilization in Costa Rica

Abstract

Objective:  To update the microbiological and physical-chemical criteria for well and spring water used for potabilization, through analysis of data collected from 965 wells and 3.292 springs during the period 1996-2010.

Methodology:  In order to fulfill the study objective the following phases were performed:

-Inventory of the diverse springs used for potabilization according to historical data available at the National Water Laboratory.

-In the case of microbiological criteria, averages were determined separately for springs and well water for the parameters of fecal coliforms (CF/100mL) and Escherichia coli (E. coli).

-With the average data for CF/100 mL and E. coli/100 mL, statistical analyses were performed for well and springs and the average, mode, median, standard deviation (SD), 

minima, maxima and range were determined; in addition the percentile distribution for each indicator was determined.

-For physical-chemical quality, we recurred to expert criteria gathered through work with water sources in the country and the scientific updates in the 4^th Edition of the WHO Drinking Water Quality Guidelines (2011).

Results:The data and statistical analysis show the convenience of having separate microbiological criteria for well-water and springs.  However, regarding physical-chemical aspects, 11 basic parameters were defined (organoleptic, hardness, nitrates, heavy metals, chlorides, and pesticides.

Conclusions: This study allowed broadening the criteria for well-water and springs used for potabilization, through analysis of current conditions of groundwater in the country.