Although the special region of Jakarta Province (DKI Jakarta), Indonesia, has a large population of 10.9 million, piped water coverage remains at only 64%. Therefore, excessive groundwater abstraction has caused serious land subsidence over the last few decades. This study proposed the priority areas for piped water supply extension to alleviate the adverse effects of groundwater over-abstraction in DKI Jakarta. Water consumption and multilayer analyses (e.g., geology, groundwater abstraction, groundwater level, piped water coverage, and groundwater quality) were carried out to determine the priority areas for piped water development. Based on three parameters, namely the water demand–supply gap, land subsidence, and groundwater quality, the northern and western regions of Jakarta were selected as the priority areas for piped water development, followed by the southern and eastern regions. The demand for piped water by the population in the abovementioned priority areas is estimated to be 462,211 m³/d, while the total water demand of Jakarta is 1,878,899 m³/d, which is greater than the supply capacity of 1,747,440 m³/d from the existing water treatment plants. Therefore, the areas for controlled groundwater abstraction were also selected to augment the shortfall of the piped water supply capacity.

Although drinking water is the main source of fluoride intake, recent studies reported that fluoride intake from foods could also be high, depending on cooking methods. In this study, we quantified the fluoride accumulation in foods soaked or boiled in fluoride-containing water and assessed the fluoride intake in different age groups from food and drinking water. We observed that, in the case of rice soaked in fluoride-containing water, more fluoride was accumulated in the rice than previously estimated. Fluoride interferes with the iodine staining process of rice, indicating fluoride adsorption. Fluoride accumulation in rice and vegetables increased when the soaking temperature was raised to 100 °C due to the gelatinization of rice grains and softening of vegetables. Ingesting foods boiled in fluoride-containing water increased the fluoride intake per body weight of infants more significantly than that in children and adults due to their low body weight. These results indicate that soaking and boiling foods in fluoride-containing water significantly increases fluoride intake compared to previous estimations. Therefore, it is necessary to re-evaluate the fluoride intake from food and drinking water considering the methods used for cooking food in each country and region.