That is going to vary wildly depending on where the people noticing live. If the location is a rural/very small town where people are self sufficient and they burn their own garbage or drive it to a dump themselves and have to watch out for bears, then just the missing people would be noticed. If we're talking about a large city liberal shit hole where they constantly over spend and are always over budget and inefficient and have a bunch of people "working" to essentially just collect a pay check, then just the death of a few productive people would be felt as they were the ones doing most of the work. Generally 20% of people produce 80% of results. In a liberal shithole, it is probably something like 5-10% producing 90-95% of the results. So you wouldn't need very many deaths in net people to be royally screwed. Go into the public records where you live, or call city hall or whatever, and find out how many garbage collectors there are. Then find out how many homes each on can service in a day. Find out how many homes there are in your city and how many garbage collectors are needed to get through each home in a week. Then you can figure out how many garbage collectors would need to die before changes had to be made such as collection every 2 weeks, or 3 weeks or a month. Now you can use basically the same method for other services to get a general idea for where you live. For the power, that could be a it tricky as you'll need to consider if your area generates all of it's own power or if it comes in from other areas, so you'll need to factor for death rates where the power comes from. With deaths though, less power will be getting used, so there is that to consider as well.