Private well and septic

For homes that get water from their own well and send it to their own septic tank. Start from the problem, or from the part of the system.

Steel well casing with a vented well cap in a lawn covered with autumn leaves
A private well in Loudon, New Hampshire: the casing and vented cap are all that show above ground. Photo: U.S. Geological Survey, New England Water Science Center (public domain).

By problem

No water, or the pump won't stop

I have a lab report

I'm replacing something

The power is out

How a private well system fits together

Each part has its own failure modes, which is why the guides follow the same order, from the breaker down to the pump.

How a private well system fits togetherCross-section: a house with a basement holding the service panel, control box, pressure switch, gauge, pressure tank and water treatment; a buried line runs to a pitless adapter on the well casing; inside the casing a drop pipe with a check valve leads down to a submersible pump below the pumping water level.water-bearing rock or gravelto tapsstatic levelpumping level12345678910
Simplified and not to scale. Redrawn after the "Basic Water System Components" figure in Franklin Electric's AIM Manual (2026 edition, p.2). In jet-pump systems the pump sits above ground and pulls water up instead.
  1. Service panel and pump breaker Feeds the pump circuit at 115 V or 230 V.
  2. Control box Starting parts for 3-wire single-phase pumps; 2-wire pumps have none.
  3. Pressure switch Starts the pump at cut-in and stops it at cut-out.
  4. Pressure gauge The first thing to read when water stops.
  5. Pressure tank Stores water under an air charge between pump starts.
  6. Water treatment (if fitted) Filters or softener, chosen from a lab test.
  7. Pitless adapter and buried line Where water leaves the well casing underground.
  8. Drop pipe and check valve Carry water up and hold pressure when the pump stops.
  9. Submersible pump and motor Sized for flow and total dynamic head.
  10. Static and pumping water levels Water level at rest, and lower while the pump runs.

Guides and tools by topic

All water calculators

  • Septic pumping & tank size
    How often to pump by tank size and household, and the minimum tank size by bedrooms from five published tables.
  • Water softener size
    Grains per regeneration from hardness, iron, manganese and household use, with salt per year.
  • Pressure tank size
    Drawdown needed for your pump and switch setting, and which published tank models meet it.
  • Well pump size & total dynamic head
    Flow your house needs and the head the pump must deliver it at, with jet vs submersible limits.
  • Well pump wire size
    Smallest copper wire for your motor and cable run, from Franklin Electric’s cable-length table.
  • Well water test results
    Enter a lab report: each number against EPA limits, public-health steps first, then treatment order.
Truck-mounted drilling rig with its mast raised on a grassy roadside site
A truck-mounted rig drilling a new well. Photo: U.S. Geological Survey, Ohio-Kentucky-Indiana Water Science Center (public domain).