Waste management is an important key to protect the environment and human health. Landfilling is the oldest form of disposal of waste and due to that Sweden has about 2000 closed landfilling sites. Closed landfilling sites might have negative impact on the environment and must therefore be monitored to reduce the risk of pollution. A way to monitor a closed landfill site is to analyze the surrounding waters and ground waters to see if the leaches might affect them. This study aims to determinate when a closed landfilling site might be considered safe enough to stop monitoring. The landfilling site at Ersmarksberget has been used as an example. A screening has been performed in the ground water and analyses from 2007-2020 have been used to determinate how or if the landfilling site affects the surrounding waters. Metals, persistent organic pollutants, and nutrients have been analyzed. The result of this study tells us that the landfilling site do not have a great impact on surrounding waters. Some concentrations of metals are higher in waters in the landfilling catchment area compared to a reference sites, but most of the pollutions are not above the environmental quality standards set by Swedish authorities. If the negative effects of a closed landfilling site are a bare minimum it might be time to stop the monitoring. To protect the environment and human health it is better to monitor and to remediate sites that are affecting the environment in a severe way.