Anarchists don't believe in a state. That does not only mean that we don't believe in the government. It also means we do not see use in the centralisation of power and responsibility. This is a good example of that.

In an anarchist society, there would be no sewage workers and other job-havers. We would live in communities, where everyone takes up partial responsibility for the maintenance of the community. You might not want to commit eight hours a day to do sewage work, but what about four hours a week of dirty work? Elinor Ostrom did a lot of research into common pool resources that has shown under certain circumstances everyone does buy in.

We already allocate some work towards parts of our job we do not like (hell, pretty sure loads of people people spend more time in traffic than it would require). It's not that big of a stretch to believe we would do so in maintaining community infrastructure. Especially if it is a shared responsibility. Even people who work "dirty jobs" full time tend to have high job satisfaction as long as they have good work conditions and a strong sense of community and collaboration.

Failing that, social systems can regulate labour through camaraderie and expectation of reciprocity. If someone does not pull their weight in a relationship, you talk about it and set boundaries. In an anarchist society, you would do the same. You want to be part of the community? You better be doing your bit to help or you aren't welcome.