Helsinki Region Environmental Services Authority (HSY) is the largest environmental services provider in Finland, serving the Helsinki metropolitan area and one-fifth of the country’s population. Annually, we collect 45,000 tons of biowaste from households and process it at the Ämmässuo Eco Industrial Center. The efficiency of the collection system in the Helsinki region relies on a good coverage of door-to-door-collection. The waste management regulations of Helsinki Metropolitan Area were given first time in 1984 (Helsinki Metropolitan Area Council, YTV, 1984). These regulations did not include source separation regulations but only for example regulations for wastebin types, emptying frequency and how to handle waste on the property. In 1998 source separation regulation for biowaste was added to the regulations. From 1998 on, residents in apartment buildings having 10 or more dwelling units were regulated to source separate their biowaste. The next step took place in 2006 when regulation for cardboard source separation for residents of apartments buildings having 20 or more dwelling units. The source separation regulations for glass and metal packages were added in May 2012 and at the same time regulation for cardboard was expanded to cover also apartment buildings of 10 of more dwelling units. The collection service for plastic packages started in 2016. No source separation regulations were given for plastic packages at that time, but households were encouraged to source separate plastic packages on voluntary basis. The next noticeable change in household waste source separation regulations took place in 2021 when source separation of packaging waste and biowaste was expanded to cover all households living in apartment buildings of equal or more than 5 dwelling units. From July 2023 on the source separation of biowaste became obligatory also for one family houses and apartment buildings of dwelling units between 2–4. HSY has investigated the amount and content of the household mixed waste from 1996 on to find out what is the effect of source separation regulations to content and amount of the mixed waste generated in households at Helsinki metropolitan area. In the latest study executed in 2024 (Helsinki Region Environmental Services Authority HSY, 2025), the average amount of mixed waste per capita was 126 kilos while for example in 2007 the amount was 165 kilos. How ever even if the mixed waste generation has increased, the amount of biowaste in mixed waste is still quite high, 41.6 kilos that corresponds to 33.1%. The results and analyze of these investigations in detail are presented in this paper.