Untreated sewage has to be injected into the soil or worked into the soil where micro-organisms can get to work breaking it down ... only treated sewage can be pumped straight onto the fields ... it's actually a strictly regulated operation thank goodness.
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https://www.gov.uk/government/publications/sewage-sludge-on-farmland-code-of-practice/sewage-sludge-on-farmland-code-of-practice