When you install your well, drainfield, and/or septic tank, you must observe minimum isolation distances as indicated in this table. In some cases, isolation distances must be increased.
Note: If your property is hilly, the well should be located up hill from the drainfield or upstream from your drainfield site.
Minimum Isolation Distances
Item
Septic Tank
Drainfield
Well**
Property Line
10 feet
10 feet
n/a
Building Foundation (no basement)
5 feet
10 feet
3 feet
Basement Wall
10 feet
15 feet
3 feet
Water Supply Well* (25 feet deep or more)
50 feet
100 feet
n/a
Lake or Stream
25 feet
50 feet
**
* Isolation distances will be increased for wells serving other than individual dwellings, and may be increased if wells are drawing water from an unprotected aquifer.
** A well cannot be located in an area subject to flooding.