This study aimed to determine sludge sewage and its potential as a solid fuel with a case study of Jakarta City. It was conducted by taking the samples of fecal sludge for three consecutive days at peak hours. The age of the sludge used in this study was 0 d, which was taken at the wastewater treatment plant (WWTP), septic tank, and open defecation. The generation of fecal sludge in Jakarta in 2020 could reach 2,129 ton/d. The quality of fecal water discharged into the environment can improve from year to year, accompanied by poor treatment. Based on the quality standards of wastewater produced from WWTP, septic tanks and open defecation do not meet the quality standards of wastewater. If this condition continues, it will pollute the water bodies in Jakarta. One alternative that can be done is to use fecal sludge as fuel. The feces water content in this study reached 74.14 ± 4 (WWTP); 68.14 ± 3 (septic tank), and 82.49 ± 1. The results of the measurement of the calorific value of WWTP, septic tank, and open defecation reached 2,620.67 ± 54 kkcal/kg; 2,853 ± 130 kkcal/kg; and 2,298.67 ± 99 kkcal/kg, respectively. The amount of energy used for Jakarta can reach 1,024,049 MJ/d. The 90 significance analysis of BOD, COD, and air content parameters affects the calorific value of feces sludge. © 2022 Desalination Publications. All rights reserved.