3. Sampling

The sampling sites were monitored at selected points according to the criteria of representativeness, access, importance, and physicochemical characteristics. In the points that had current such as rivers, sewers, and channels, composite sampling was carried out, whereas specific samples were taken in the dams and wetlands. Table 1 shows the number of points and their description and observations.

Samples were taken at the defined points on the dates scheduled for four monitoring days during the periods of August to December 2015 and February to May 2016. The method used


Table 1. Number and type of points selected for each component of the urban water cycle of the city of Bogotá.

to determine the flow in terms of area by velocity was to take a sample every hour for a period of 8 h, recording the values of flow rates and parameters at the measuring site (pH, conductivity, salinity, and oxygen). In drinking water, it was necessary to seek the assistance of the users of the system, who were trained to take the samples in their homes; these samples were subsequently collected for analysis.

At the exit of the reservoirs used as sources of supply, rainwater channels, sections of the Bogotá River and its tributaries, we used windmills. In the wetlands, samples were taken at different points in the water mirror and in the exits and entries that could be identified, taking into account that the latter are composed of large areas of water and in some cases are fractioned. Two liters of water were taken for each sampling point in each campaign in amber glass bottles of 1 l capacity, refrigerated, and taken as soon as possible to the laboratory for preprocessing.
