T There has been an expansion of a flood area in West Jakarta. It was found there are four factors that affecting flood area e.g:built up area (costructed land), topography, soil type, and drainage. Transformation of natural areas to build up areas, topografic condition wich almost flat with sea water levels, clay soil type that has a high degree of plasticity, and an inadequate drainage system cannot accommodate tehe water, are the causes of flooding. from the four factors only drainage can be interfered. To reduce flooding in West Jakarta. The suggestion is to plan dan designing the drainage system network.