Published
Half of Idaho's well rules are standing in your yard, visible from the porch
The rule has opinions from the grass line down
Idaho’s well construction standards are not a suggestion attached to a permit — they are the conditions the driller attests to, in writing, when the well is finished. Most of them live quietly underground. Several of them are standing in your yard right now, and you can check them without a shovel:
“For all wells the casing must extend at least twelve (12) inches above land surface and finished grade and to a minimum depth below land surface as required by these rules. Concrete slabs around a well casing will be considered finished grade.”
— IDAPA 37.03.09 §025.04, Idaho well construction standards rules, current through the 7-1-25 docket. Retrieved 23 September 2026
That one sentence settles a recurring lot argument: a well does not disappear into the lawn. The pipe stays a foot above the grass, the gravel, or the concrete — and the owner’s duty in the same rule is to keep it there, along with a proper cap, for the life of the well.
The casing: what the hole is lined with
- Every well gets casing — and it must be new or like-new, defect-free, and marked by the manufacturer with its specifications.
- Steel must meet ASTM A53 Grade B or API 5L Grade B, with a minimum wall of 0.250 inch on the common sizes and depths (thicker at large diameters and depth). Joints are welded watertight or screw-coupled, and stick welds need a minimum of two passes.
- Plastic (thermoplastic) casing is allowed only where the bottom-hole temperature is 85°F or less, rated SDR-21 or Schedule 40 at four inches and under — and wherever it stands above ground it must be protected inside steel casing reaching at least 18 feet down.
- Plumb and straight enough that screens, liners, pumps and pump columns can go in and come out without harming the equipment.
The three things bolted to the top
- The cap. Before the rig leaves, the casing top must be closed with a welded ¼-inch steel plate carrying a ¾-inch threaded, plugged access port, a threaded cap, or a commercially manufactured watertight sanitary well cap — a snorkel-vented version where water can submerge it, or a state-approved control valve where the well flows on its own.
- The access port. A port you can measure depth-to-water through, or an approved pressure-gauge fitting on a flowing well. The rule closes the shortcut explicitly: “Air lines are not a satisfactory substitution for an access port.”
- The tag. A stainless steel well tag, permanently affixed — welded full-length across the top and down each side, or fastened with four stainless closed-end rivets.
A well with a foot of steel above grade, a sound cap, a measuring port, and a legible tag is a well built to the book’s last page. Anything else is a question worth asking of the licensed driller who built it.
Sealing the aquifer shut
The invisible half of the rule is about keeping water from moving where it should not. Where artesian pressure exists:
- Casing must be sealed from land surface to at least 38 feet, with seal material carried five feet into the confining layer above the producing zone.
- A well that flows at the surface must carry a state-approved control device able to stop the flow completely.
- The driller may not leave the site until those requirements are satisfied.
Where the well may sit
The rule carries its own siting distances on the well side of the fence: 20 feet from above-ground chemical storage tanks, 50 feet from permanent or intermittent surface water, and 25 feet from canals, irrigation ditches and laterals. The septic-side rows — the tank, the drainfield, the sewer lines — are the separation tables this site prints in full, and the well rule deliberately points at them rather than replacing them. A waiver of a specific standard is possible, but it takes a joint written request from both the driller and the owner, signed, with the state answering within ten business days.
When a well retires
An unused well is not a closed chapter — the owner is charged with maintaining it or decommissioning it properly: a licensed driller, state authorization first, seal material filling the well (perforating the casing every five feet where needed so grout reaches the voids behind it), and a report to the state describing the work. The owner’s continuing duties run alongside: no permanent building within 10 feet of the well except one housing the well itself, the casing height and cap kept up, and a well that becomes unusable repaired or decommissioned rather than left open — the same protective instinct behind the abandonment rule for old septic tanks.
The walk-around before you buy
- Look for the foot of stick-up — casing cut off at grade is a finding, not a style.
- Identify the cap: sanitary, threaded, or welded plate with its plugged port.
- Find the tag and read it — it is the well’s name in the state’s records.
- Confirm the access port exists so water level can be measured without invention.
- Then bring the file — not just the walk-around — to the septic-and-well questions before closing: (208) 656-1467.
Common questions
How far above the ground does a well casing have to be?
At least twelve inches above land surface and finished grade, with concrete slabs around the casing counted as finished grade. The owner's duty in the same rule is to maintain that height and the proper cap for the life of the well.
What kind of casing does Idaho require in a well?
Casing in every well, new or like-new and clearly marked by the manufacturer. Steel must meet ASTM A53 Grade B or API 5L Grade B with a minimum wall of 0.250 inch on common sizes. Thermoplastic is allowed only at bottom-hole temperatures of 85 degrees or less, rated SDR-21 or Schedule 40 at four inches and under, and protected above ground by steel casing extending at least 18 feet down.
What covers the top of a legal well?
Before the drilling equipment leaves the site, the casing top must be closed with a one-quarter-inch welded steel plate carrying a three-quarter-inch threaded and plugged access port, a threaded cap, or a commercially manufactured watertight sanitary well cap - snorkel-vented where submergence is possible, or a control device where the well flows.
What is the stainless steel tag on a well casing?
A state well tag the driller must permanently affix at completion - welded across the top and down each side, or fastened with four stainless steel closed-end rivets. It links the physical well to its state record.
Does a well need an access port?
Yes. Upon completion the well must allow measurement of depth to water through an access port, or of shut-in pressure through an approved gauge fitting on a flowing well. The rule states plainly that air lines are not a satisfactory substitution.
Can a well construction standard be waived?
In unique cases the director may waive a specific standard where ground water will still be protected. The driller and the well owner must jointly submit a signed, detailed plan identifying the rule to be waived, and the director responds within ten business days.
How close can a building be to a well?
Ten feet, under the owner's responsibilities in the well rules - except a building whose purpose is housing the well or its plumbing. On the septic side, the separation tables this site prints separately govern tanks, drainfields and sewer lines.
Who is responsible for an old unused well?
The owner. An unusable well must be repaired or properly decommissioned by a licensed driller under a state permit - filled with approved seal material, with the casing perforated every five feet where needed - and reported to the state afterward.