Flat Flange Deep Well Pump Basics

Use the Flat Flange Deep Well Pump System if your well specs meet one of these scenarios:

Static Water Level:250′ or less
Well has a Casing:No
Static Water Level:250′ or less
Well Casing is Below Grade (Ground):Yes
Static Water Level:250′ or less
Water Source is a Tank or Cistern:Yes
Freezing is an Issue:Yes


The Bison Pumps Flat Flange Deep Well Pump System is a Side-By-Side system (Side-By-Side Deep Well Pump Basics) that can be installed in the same well casing as your electric submersible pump system. It is a Freeze Proof pump system that can deliver you with Pressurized Backup Water when used in conjunction with the Pressurizing System. This provides you with water inside your home accessible to any water feature such as a toilet or sink! It can lift water from 250 feet deep using the standard handle or up to 300 feet with the addition of the Heavy Duty Pump Head option.

The Bison Pumps Flat Flange Deep Well Pump System is designed to be used in situations in which attaching the pump head directly to the well casing is not possible. This can occur when the well is a dug well with no casing. Often these are older wells with large openings. Another situation could be when wells are installed below grade. These wells do have well casings and may even have electric submersible pumps installed. However, you cannot install the pump head onto the well casing since that would put it partially below grade making the pump inaccessible.

Dug Well Without Casing
Well Casing Below Grade

A rarer situation is when a tank or cistern is the water source, and the pump must be installed in such a way that it is exposed to the elements. Normally we would recommend the Model 1900 Stainless Steel Pitcher Pump shallow well pump. However, the exposure to freezing temperatures prevents that recommendation. Instead, a deep well system must be utilized.

Well Pump Adapter

Flat Flange Pump Mounted on Structure

The Flat Flange well pump adapter is designed to be bolted onto a surface with a gasket between the flange and the mounting surface. There must be a hole in the mounting surface large enough for both the pipe and the cylinder to pass through. We recommend a hole greater than 3 1/2 inches in diameter. View our recommended flat flange hole pattern. Typically, customers build a structure over the well that is within the recommended heights (12” – 18”) above grade. The cylinder and drop pipe and rod are fed through the access hole and installed in a normal fashion. The difference comes when it is time to secure the pump head. It is bolted to the structure, which must be strong enough to prevent any motion when the pump head is pumped during operation.

For wells that have well casings below grade, the well casing well cap must be replaced with one that has an additional access hole to accommodate the drop pipe and rod that will pass through it to get inside the well. This maintains the integrity of the well seal. See attached diagram for this setup.

When the water source is a tank or cistern, the flange would be attached to the tank surface (assuming it is at an appropriate height for operation). Otherwise, it too would need a structure built over the access hole to raise the pump head to an operating height similar to the installed pump photo above.

Drop Pipe and Rod

Each Bison Pumps Side-By-Side Flat Flange Deep Well Pump System comes with enough eight (8) foot sections of Drop Pipe and Rod to reach approximately 20 feet below the static water level. This depth allows for fluctuations in the water table and ensures that the cylinder will be below the water surface. The size of the Drop Pipe is typically 1 1/4” but we do offer and recommend 1” for certain applications. This would be where inside casing space availability is a concern or the static water level exceeds 160 feet.

Note that the deeper the static water level is, the more drop pipe will be required. This directly impacts the cost and design of the system. This is why a fixed cost for a pump system cannot be provided. Each pump system is unique to the customer’s well specifics.


One appropriately sized cylinder is included in a Side-By-Side Flat Flange Deep Well Pump System. In a Lift Pump system, like the Side-By-Side Flat Flange, the actual “pump” is the cylinder. This is the device that creates the vacuum to draw water into the water inlet and then uses its piston assembly to lift the water up the drop pipe. In a Side-By-Side application, the size of the cylinder is determined by space available inside the well casing (if there is one) and the static water level. We use this Standard Cylinder Selection Chart to determine the appropriate size for each customer’s situation.