Backgroud: Port-a-Cath catheters have been widely used in the clinical systemic therapy of cancer owing to the level of safety and effectiveness provided to patients during the treatment. The current study aimed to evaluate the decrease in risk of infection and the permeability condition of totally implanted catheters by using distilled water in the maintenance of Port-a-Caths. Methods and findings: Over the period between November 2008 and October 2014, a total of 109 patients with Port-a-Cath were attended to at the Ambulatory Chemotherapy Treatment Center from the Santa Marcelina Hospital in São Paulo, Brazil. The focus was on patients who had the totally implanted catheters, encompassing not only the treatment itself but also the maintenance of the devices. From the total sample, only 5 patients (4.6%) had catheter infection. Statistical analysis was performed using STATA 11.0. Conclusion: the use of distilled water in the maintenance of a Porta-Cath has suggested to be effective and safe regarding infection risks and the device permeability.