there are many things that break down organically, and when composted they do it more faster, but in a way that it can be reused for multiple purposes. here is what i have learned from researching the topic, its been a year or so but here goes.
hot showers: compost piles of leaves and other organics can provide for hot showers. what is required is an actively composting pile, a lot of hose to loop and circle within the pile then up to the shower head. this looping in the compost creates warms because of what happending as the materials break down, thehy create heat. the temp within a composting heap is highas this goes on so that can be utilized.
fertilizer: even human waste can be used to accomplish this. any kind of food scraps or waste can be added to compost (pretty sure). dead plants can be added, then reused next season.
about human waste:out houses or bathrooms, whatever we decide on, would benefit from saw dust were to to compost it. it helpscover the smell and breaks down in compost. once full, we start a line of buckets, then age em to compost. i know it sounds hella gross but peole been doing it since forever so whatvere. its better than what i have available in the city anyways.
i may have forgoten a lot, but theres tons of vids on youtube about homesteading, composting, and living a natural life.
if i forgot something ill add it. if you have anything to add add it.