Reclaiming of land is done using a process known as landfill. Singapore imports sand from Indonesia, which is used to fill the seabed. However, sedimentation can occur. Sedimentation occurs when the particles of the sand erode away due to wave currents and gravity.

Sedimentation causes the water to be cloudy, not allowing much sunlight to enter the water. Aquatic plants such as phytoplankton and coral reefs require sun light. Without sunlight, many of them die. Materials that are used for landfill are also poor in nutrient and lack organic material. With such a large input of poor nutrients into the water, it upsets the nutrient cycle. One found that the sediments caused an influx in the release of nitrogen gas and other nitride compounds. Nitrogen causes a decrease in the pH value in the water and many organisms are not adapted to surviving in an acidic environment, causing a decrease in amount of aquatic organisms.

Sedimentation has not only caused a great deal of damage to the Singapore waters, it has also impacted neighbouring countries. Malaysian fishermen reported a decrease in the quality the water they fish in and a decrease in the amount of fish they are able to catch. They posited that this could be due to the increase in sediments in the water due to land reclamation in the nearby coasts of Singapore. Even though the true cause of the decrease of fish is debatable, increase in sediments can indeed cause such a phenomenon.