I never had sewer until I moved here. Upkeep of the lines is pricey. I NEVER had a problem with a septic system....I wish the law allowed that option.
Another huge source of contamination that gets into rivers and lakes is the chemicals that people put on their lawns. There isn't even a reason for that. A well-chosen grass for the environment and soil conditions does not need fertilizers or plant foods.
What upkeep? Is your house real old?