Pitless Unit
Best for New Installations
A complete, heavy-duty system designed for new well installations and easier future pump service.
Choose Pitless UnitPay More Now. Fewer Headaches Later.
Find the Right Pitless UnitA complete, factory-tested pitless system built for dependable installation, easier well access, and simpler future service.
- Factory Pressure Tested
- Full-Diameter Well Access
- Built for the Long Haul
- Multiple Sizes and Lengths Available
For new wells and long-term installations.
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Why Does the Merrill Pitless Unit Cost More?
Because it is more than a basic pitless connection.
- Water Flow Parts
- Casing Included
- Holds More Weight
- Easier Future Service
Pitless Unit, Kit, or Adapter?
Choose the option that best matches your installation, replacement needs, and existing well setup.
Pitless Kit
Best for Complete Replacement
A bundled option for installations that need the adapter and supporting internal components together.
Choose Kit
Pitless Adapter
Best for Replacing an Adapter
A practical choice when economy is important compatible with many casing sizes 5" or larger.
Choose AdapterHow to Select Your Pitless Unit In 3 Simple Steps
Step
1
What Is Your Casing Size?
Select the pitless unit that matches the inside diameter of your well casing.
Step
2
What Is Your Bury Depth?
Measure from finished grade to the centerline of the service-line connection.
Step
3
What Are Your Drop-Pipe and Discharge Sizes?
Match the pitless unit to the sizes of your drop pipe and underground service line.
Compare Pitless Units
Which Merrill Pitless Unit Is Right for You?
Four proven options. The same dependable Merrill quality.
SP
Time Proven
The proven, field-favorite design for most well installations.
Shop SPSPP
Illinois Code Approved
The proven SP-style design configured to meet Illinois code requirements.
Shop SPPSSMCU
Clear Access for Well Chlorination
The removable internal assembly leaves the well casing unobstructed, making chlorination and future service easier.
Shop SSMCUH2O
Pitless Control Unit
An integrated control solution designed for expansion-tank and variable-frequency-drive mounting. Inside the well.
Shop H2OInstallation Overview
SP Pitless Unit Cross Section
See how the Merrill SP Pitless Unit creates a secure underground water connection while allowing the internal assembly to be serviced from the top of the well.
What Comes With a Merrill SP Pitless Unit?
Each component is designed to work together as one complete system for installation, support, sealing, discharge, and future well-pump service.
Factory-Assembled Upper Casing
The complete outer casing supports the pitless-unit assembly and creates the foundation for the underground connection.
Internal Complete Assembly
The removable internal assembly supports the drop pipe and allows the well pump to be accessed from the top.
Sealing or Adjustment Hardware
Moves the seals into the discharge to secure the internal assembly and complete the discharge connection.
Top Support Plate
The upper support plate secures the internal assembly and helps support the connected drop-pipe system and pump.
Well Cap (When Selected)
Select configurations can include a well cap to cover and protect the top of the completed well installation.
Pitless Unit FAQs
Common Questions
1. Why Choose a Pitless Unit Over a Kit or Adapter?
- Pitless unit: The most complete, heavy-duty option for a new well installation.
- Pitless kit: Adds the components needed to retrofit or complete an existing well casing.
- Pitless adapter: A lower-cost and more common option, but it requires additional parts and installation work and may be harder to service later. It requires a 5-inch well casing or larger.
2. Is a Pitless Unit Worth the Extra Cost?
Yes. A pitless unit costs more upfront, but it provides a stronger, more complete system that is factory pressure tested, easier to service and designed to avoid costly digging later.
3. What Comes With a Merrill SP Pitless Unit?
Merrill SP Pitless Units provide the major components needed to create a secure underground water connection while supporting future pump access and service.
4. Can a Well Pump Be Serviced Without Digging?
Yes. Merrill pitless units are factory tested to ensure reliable future service without digging.
5. Can I Install a Pitless Unit Myself?
Pitless-unit installation is typically a job for a qualified well driller or pump installer. The unit must be correctly sized, positioned, sealed and connected to the well casing. This protects the well system and water supply.
6. How Long Does a Pitless Unit Last?
A quality pitless unit can last the life of the well. Its lifespan depends on proper installation, water conditions, corrosion exposure, material selection and how heavily the well system is used.
7. How Do I Know When a Pitless Unit Needs to Be Replaced?
A pitless unit is typically only replaced if the top of the well is damaged.
8. Can a Pitless Unit Handle Corrosive Water?
Yes, but choosing the correct material is important. Tell your well contractor about corrosive or aggressive water conditions so they can select the appropriate pitless unit and compatible system components.
9. Why Choose a Complete Pitless Unit Instead of Separate Parts?
A complete pitless unit is engineered to function as one system. It supports the drop pipe, creates the underground water-line connection and makes future well-pump service easier. No field welding is required.
Complete Well System
Build It Right Once. Service It More Easily Later.
Shop Merrill Pitless Units →A complete pitless unit creates a strong underground water connection while allowing the pump and internal assembly to be serviced from the top of the well. That means fewer separate components, easier future access, and less risk of costly excavation.