Guillen stated to local media that President Rodrigo Chaves-Robles asked for his resignation personally.

Following Guillen's departure, the government appointed Juan Manuel Quesada-Espinoza as the next president of the Water Institute.

Quesada was the president of the Costa Rican Petroleum Refinery (Recope), a state-owned firm that distributes, produces, and imports oil and derivatives.

This week, specialists from the Ministry of Health, the Water Institute, the Ministry of the Environment, the University of Costa Rica, and the Ministry of the Environment are running tests on the water plants to establish which sort of hydrocarbon polluted the water.

Chemical tests have eliminated the possibility that the pollution was caused by hydrocarbons such as benzene, xylene, or toluene. However, as of Tuesday, pollutants were still present in the chemical test findings.

Due to the significant risk of ingesting polluted water, more than 107,000 people must continue to collect drinking water supplied by the institute's water tank trucks.