The short answer
If your Bonneville County lot is outside city water and sewer, plan on a private well and a septic system before the house goes up. Guardian’s working budget is $15,000–$25,000 for a rural well and $10,000–$15,000 for a standard septic system. The soil evaluation can push septic higher. Both are permitted separately from the building permit.
Who permits what
- Septic: Eastern Idaho Public Health (EIPH). EIPH evaluates the soil, then decides the drainfield size and system type, either a standard trench or an alternative system. Counties in the region want septic approval in hand before they issue a building permit, so it sits at the front of the schedule.
- Well: Idaho Department of Water Resources (IDWR). The well needs an IDWR permit or driller start card. Some county checklists don’t list it, but you can’t occupy the home without it.
- Building permit: the county or city. Your site plan has to show the well, the septic tank, the drainfield and its reserve area, and the setbacks between them.
What to budget
| Item | Working range |
|---|---|
| Well, where a rural well is needed | $15,000–$25,000 |
| Standard septic system | $10,000–$15,000 |
| Water line, house to well (1”) | $25 per linear foot |
| Sewer line | $28 per linear foot |
The septic system type is set by the soil evaluation, and an alternative system costs more than a standard trench. Distance also adds up. A home set far back from the road, or far from the well, pays for every foot of trench between them.
City services vs. rural lots
Most lots inside Idaho Falls, Ammon and the established subdivisions connect to city water and sewer. You pay connection fees in place of drilling and a drainfield. If you’re choosing between two lots, find out which side of that line each one is on before you compare prices. The rural lot usually has to carry tens of thousands of dollars in well and septic costs that the city lot doesn’t.