Sweden today have about 700 000 sewer systems, among which half of the plants are considered inefficient. The wastewater contains nutrients such as phosphorus and nitrogen, which in turn contribute to the eutrophication of waters. According to the Water Authorities, there are 650 waters in the northern district of the Baltic Sea that suffers from eutrophication. Close by these waters it is common with smaller treatment plants for sewages. It is up to the monitoring authority to decide which degree of purification the plants need and to supervise. There are different monitoring methods of small treatment plants and it is up to each municipality to choose their way, which means that monitoring is very different between different municipalities. The purpose of this study is to identify how different municipalities preform monitoring. It is aimed to investigate the need of a more effective monitoring for Norrtälje Municipality and to see if any of the methods from the other municipalities may be suitable. Examination has been done through participation in sampling projects, survey and compilation of data from VISS. The survey showed that monitoring practices in the municipalities differ greatly since the number of smaller treatment plants and resources differs. Data from VISS shows that the need for monitoring is high since 68 waters in Norrtälje won´t reach good status until 2021. Previous projects show that the authorities find it hard to do the sampling by themselves but there is a high demand for such methodology.