This is the national waterworks and sewerage authority aka NAWASA aka MWSS (metropolitan waterworks and sewerage system).
This structure is located at central, arroceros , at the back of city hall and infront of Central station.

more added info:

The Manila Water Supply System began its task of providing a steady and potable water supply for Metro Manila since 1878, back then, it was still governed by Spain.

It is the oldest system in Asia.
Constructed in 1878 with funds donated by Spanish philanthropist Francisco Carriedo y Peredo, the MWSS began its task of providing water on tap to what is now Metropolitan Manila by delivering 16 million liters of water daily.

the sign that says Bulwagan ng Katarungan means : the Hall of Justice.
you might be wondering why is there a hall of justice inside the sewerage office?

beats me...i have to idea either. ^-^
so i think i have to re-visit the area when i have the time.