Pitless Adapter: What It Is & Signs of Failure
What Is a Pitless Adapter?
Purpose
The pitless adapter is a two-piece fitting that:
- Connects drop pipe (vertical) to water line (horizontal)
- Provides frost-proof water connection below ground
- Maintains sanitary seal in well casing
- Allows pump removal without excavating
Why "Pitless"?
Before pitless adapters, wells needed a "well pit"—an underground room to access the water line connection. Pitless adapters eliminated the need for pits (which were unsanitary and prone to contamination).
Location
- Installed through side of well casing
- Below frost line (varies by region)
- Typically 2-6 feet below ground surface
How It Works
Two-Piece Design
- Casing half: Permanently attached to well casing with O-ring seal
- Drop pipe half: Connects to pump and drop pipe, slides into casing half
Connection Method
The two halves lock together with a watertight seal. The drop pipe half can be lifted out with a "T-handle" tool, bringing the pump and drop pipe up with it.
Why This Design?
- Pump can be pulled without excavation
- Water line stays buried and protected
- Sanitary seal prevents contamination
Types of Pitless Adapters
By Material
- Brass: Most common, good corrosion resistance
- Stainless steel: Best corrosion resistance, higher cost
- Cast iron: Older wells, less common now
- Plastic (PVC): Budget option, some limitations
By Size
- 1-inch: Smaller residential wells
- 1.25-inch: Most common residential
- 2-inch: Higher flow, larger homes
- Match to drop pipe and water line size
By Casing Size
Adapters are made for specific casing diameters (4", 5", 6", etc.). Must match your well casing.
Signs of Pitless Adapter Failure
Leaking at Wellhead
- Water seeping up around well cap
- Wet ground around well casing
- May be worse when pump runs
Loss of Pressure
- System loses pressure
- Pump runs more frequently
- Water escaping at adapter connection
O-Ring Failure
- Common cause of leaks
- O-rings age and crack
- May be fixable without full replacement
Corrosion
- Visible rust at casing penetration
- Weakened connection
- More common with cast iron
Stuck or Frozen
- Can't separate halves to pull pump
- Corrosion or mineral buildup
- May need to excavate and replace
Replacement
When to Replace
- Leaking that can't be fixed with new O-ring
- Severe corrosion
- Cracked or damaged fitting
- When pulling pump for replacement anyway
Adapter Costs
| Type | Cost |
|---|---|
| Brass 1.25" | $150-$300 |
| Stainless steel 1.25" | $250-$450 |
| Brass 2" | $200-$400 |
| O-ring kit only | $15-$40 |
Labor
- Standard replacement: Done when pump is pulled—included in pump service
- Excavation needed: Add $300-$800 if casing half is damaged
- Total with pump pull: Usually $300-$600 added to pump service
DIY Considerations
- Requires pulling pump (needs equipment)
- Must get proper size and type
- Improper installation causes leaks
- Generally not a DIY job
Frequently Asked Questions
What is a pitless adapter?
A fitting that connects your well's drop pipe to the underground water line through the well casing, below frost line. Provides frost protection and allows pump access.
How long does a pitless adapter last?
20-40+ years for brass or stainless steel. O-rings may need replacement sooner (every 10-20 years).
Why is my pitless adapter leaking?
Usually failed O-ring or corrosion. O-ring replacement may fix it; severely corroded adapters need full replacement.
Can I replace a pitless adapter myself?
Requires pulling the pump and proper tools. Not recommended for DIY unless you have pump pulling equipment and experience.
What size pitless adapter do I need?
Match to your drop pipe size (usually 1" or 1.25" residential) and well casing diameter (4", 5", 6", etc.).
Pitless Adapter Problems?
We can diagnose and replace pitless adapters during pump service.