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The POSEIDON team conducted a needs-mapping survey in Kalijaga Hamlet on Saturday (May 31, 2025), followed by a survey of local water sources on Sunday (June 22, 2025). The surveys revealed that residents rely on groundwater from dug wells 4–12 meters deep and bore wells up to 80 meters deep, with salinity levels ranging from 0.94 to 8.58 ppt. For cooking needs, residents purchase water from wells considered less brackish and suitable for use.

The mushola was chosen as the installation site for the filter so that clean water can be accessed by all residents of Kalijaga Hamlet,” said Muhammad Raihan, Chief Organizer of POSEIDON 2025.

The water filter installed at the mushola in Kalijaga Hamlet (Doc. POSEIDON Team)

The installed water filter operates through several stages of purification. Water is first pumped into a tank containing activated carbon, silica sand, and manganese greensand. It then passes through a membrane to filter fine particles. In the final stage, the water is exposed to UV light to eliminate microbial contaminants.

On Saturday (September 20, 2025), a handover ceremony of the water filter was held, from the POSEIDON team to representatives of the Mosque Prosperity Council (DKM) and the head of neighborhood unit RT 04/08. The handover and inauguration were attended by Dr.techn. Dudy Darmawan Wijaya, S.T., M.Sc., Dean of the Faculty of Earth Sciences and Technology (FITB) ITB; Dr.rer.nat. Rima Rachmayani, Head of the Oceanography Study Program, FITB ITB; accompanied by supervising lecturers Dr. Iwan Pramesti Anwar, S.Si., M.Si., and Saat Mubarok, Ph.D.; as well as ITB Oceanography lecturers Farrah Hanifah, S.Si., M.Si., Dayu Wiyati Purnaningtyas, S.Si., M.Si., and Ir. Hanif Diastomo, S.Si., M.Sc.

“I hope this filter can bring tangible benefits to the community. May the residents be able to worship more comfortably and solemnly, as the water in the mushola is no longer brackish,” said Dean of FITB.

It is hoped that the POSEIDON community service program can serve as an initial step toward sustainable efforts to address clean water issues in coastal areas. Through collaboration between students, lecturers, and local communities, this initiative is expected to raise awareness of the importance of wise water resource management and encourage the development of simple technological innovations that can be applied in other regions facing similar challenges.