Pitless Adapter: Leaks and Replacement

How a pitless adapter works

It's a two-piece fitting:

• The outer half goes through a hole in the side of the casing and connects to the water line that runs to the house. Rubber gaskets seal it to the casing wall, inside and out.
• The inner half sits inside the casing, carries the drop pipe and pump, and slides down into the outer half, where the joint seals on an O-ring.

To service the pump, a contractor threads a lift pipe into the top of the inner half, pulls it up out of its seat, and lifts the whole column out through the top of the casing. Nobody has to dig.

A pitless unit is the bigger cousin. Instead of a fitting through a hole, it replaces the section of casing from the frost line up to the surface.

Older homes sometimes have a well pit instead: a buried chamber where the pipe leaves the casing. EPA Region 8 says pits aren't appropriate in flood-prone areas or where the water table is high. A pit that floods puts surface water right at the top of the well. Converting a pit to a pitless adapter is a common upgrade.

Signs your pitless adapter is leaking

• The pump cycles with no water running. The water drains back through a bad O-ring, and pressure drops.
• Pressure falls overnight. Same cause. Rule out the check valve and toilets first; our foot and check valve page covers that test.
• Dirty or cloudy water after rain, or a positive bacteria test. A leak at the outer gaskets lets shallow ground water into the casing.
• A wet spot or sinking soil around the casing. Water escaping from the house-side connection washes out the backfill.

A leak at the outer seal is worse than one at the O-ring. The O-ring leak costs you pressure. The outer seal leak puts surface water into your drinking water.

Tools and parts

• Lift pipe (often called a T-handle or pitless tool) that threads into the adapter
• New O-ring or seal kit for your adapter's brand and model
• Gasket lube or anti-seize for the O-ring and machined surface
• Pipe wrenches
• Chlorine for disinfecting the well afterward

For a full replacement of the outer half, add a hole saw sized for the adapter. Merrill's chart, for example, calls for 1 3/4 inches on some models and up to 3 inches on others.

How a pitless adapter is replaced

Mistakes to avoid

• Dropping the column. If the lift pipe isn't threaded on fully, the pump and pipe go to the bottom of the well. Fishing them out costs more than the whole repair.
• Mixing brands. The inner and outer halves are made to fit each other. Match the make and model, or replace both.
• Skipping the disinfection. Every time the well is opened, things fall in.
• Backfilling before testing. Once the trench is full, a leak means digging it up again.

When it's a pro job

If the adapter is more than a few feet down, the pump is a submersible on a long column, or the outer half needs replacing, hire a licensed well contractor. Most pitless jobs are both. HomeGuide puts a two-person well repair crew at $150 to $300 per hour, and it doesn't list a pitless-specific price, so get the parts and labor written out before work starts. If the pump has been in for a long time, it's often smart to replace it while the column is already out. See well pump replacement.