The occurrence of algal taste and odor (T&O) compounds was investigated in three Swiss lakes which exhibit different nutrient levels from eutrophic to oligotrophic (Lake Greifensee, Lake Zurich and Lake Lucerne). Apart from dissolved T&O compounds, the study also encompassed particle-bound compounds, i.e., compounds that can be released from damaged algal cells during drinking water treatment. A combined instrumental (SPME-GC-MS) and sensory method was applied that allowed to detect and quantify T&O compounds in natural waters in the sub ppt to low ppt-range.