Hermod is absolutely correct. In the little Washington town where I'm a city councilman, we just completed a $10m project to bring wastewater treatment to the whole [[275 ERUs) town. One of the main reasons was that failing septic systems had seriously degraded our water supply.

And yes, you're taking a chance. The other justification was that it would allow for development. We're 8 miles south of the nearest "large" city and land is reletively cheap here. But without sewer, due to our soil composition, you'd need a quarter acre lot to accomidate the drain field if you want to build a single family home. With sewer, 80 X 120 works just fine. As a town of 900, we could not sustain city services without increasing our population [[read tax) base. And frankly, I'd rather take a chance on being ready for development rather than what some communities did during the last housing boom, that is, pushing development then going around and playing catch up when things begin to fail.