Today, considerable amounts of resources are landfilled or incinerated, and recyclable materials such as metal, glass, plastic, and paper are disposed of as residual waste instead of being sorted into recyclable fractions. Recycling is one way of transitioning towards a circular economy and a more resource-efficient society. However, in many older cities there is insufficient space for waste bins, which makes waste sorting difficult. The aim of the study was to test how the introduction of a new kerbside collection system, using different-coloured plastic bags, would influence the amounts of residual waste and separately collected food waste. Coloured plastic bags were introduced in an old city centre in Kalmar, in the southeast of Sweden. This type of kerbside collection was applied to 38 apartments with a total of 87 residents for four weeks. Results show that residual waste decreased directly by 15 percent and the collected amount of food waste increased directly by 35 percent. The residents perceived that the sorting system facilitated sorting and that the sorting of recyclable materials increased. Kerbside collection, close to properties, seemed to be an important factor in reducing the amount of residual waste, leading to increased sorting, and hence improved recycling.