Since arriving in Água Suja/MG in 1925, Father Eustáquio dedicated his missionary work to caring for the soul and body of the local residents.

Since the town had no doctors, Father Eustáquio used branches and homemade, natural remedies to help the sick in the village. He even received homemade medicines from Holland to use in his missionary work.

Father Jeronimo Roozen accompanied the work developed by the Blessed with the sick of Água Suja. In his testimony to the Tribunal of the Cause of Beatification and Canonization of Father Eustáquio, in 1964, he spoke about a time when he had to replace the Blessed:

“"Once, while he was absent and I was his substitute, I went to see one of his patients who suffered from asthma and heart problems; the patient told me that Father Eustáquio gave him certain lozenges; having mint lozenges at home, I administered this medicine to him, and the patient later told me that he felt better but that the medicine Father Eustáquio gave him was better than mine."”