Well Control Placement at the Wellhead

A convenient add-on to your pitless well construction.

By Lana McGee Straub, RL

Well control placement is an issue that pump professionals must consider for each installation, and there are certainly many variations professionals can choose from.

(Left) A 5-foot buried pitless control unit connected to the well casing and ready for a flow test. (Right) A variable speed drive mounted to the top lid of the well cap as typically done with a pitless control unit. Photos courtesy Steve Anderson, president of Merrill Mfg. Co. in Storm Lake, Iowa.

Historically, a common method of allowing access to the wellhead was the well pit. The main benefit of the well pit was convenient access to the lateral pipe in a place below the frost line to keep the lines from freezing.

However, the well pit can lead to unsanitary conditions, including leaching from surface contamination. This potential for contamination is one of the reasons pitless alternatives are now in use and mandated by licensing agencies.

Pitless adapters are a sanitary solution because the discharge unit is buried below ground connected directly to the wellhead, creating a watertight seal. Oftentimes, the pressure tank is also buried in the ground as well. To prevent freezing, water lines can be buried below the frost lines with the pressure tank usually buried at least partially below the frost line.

Pitless Adapter Design Revolutionized

But what if all the controls were installed in a self-contained pitless adaptation right at the wellhead?

Steve Anderson, president and design engineer at Merrill Mfg. Co. in Storm Lake, Iowa, has a solution he claims can save 50% on installation time and 10% of amp draw on the motor—placing the controls in a pitless control unit.

Anderson gave a presentation on the subject during the virtual-only Groundwater Week 2020. Water Well Journal contacted Anderson for a follow-up to his presentation and to get more details for readers on this design.

A Pitless Design

The H2O pitless control unit comes in a 12-inch galvanized steel or 12-inch PVC casing with a reducer to whatever size the well might be constructed with—4-inch, 5-inch, 6-inch, or 8-inch well casing.

For the installation, a heavy duty pitless adapter is installed in the 12-inch casing just above the reducer. Male and female connection valves are then installed on top of the pitless adapter.

The male connection valve is equipped with threads for coupling on pipe and gives the installer the convenience to pull the entire well when needed. The female connection valve seals around the male valve for piping connection to the controls.

A specialty heavy-walled, no-lead, brass cross connector is connected to the female valve which can then be connected to a surge tank, pressure relief valve, or pressure transducer to a variable frequency drive (VFD).

A surge tank is included in the configuration—in 2-gallon, 4-gallon, or 10-gallon capacities depending upon the needs of the installation. A 12-inch aluminum watertight well cap completes the H2O self-contained well control package. The well cap is designed with an aluminum universal mounting plate for VFD drives to be installed inside the 12-inch casing.

“The largest pressure tank that fits inside the control unit is a 10-gallon tank, which is all that is needed for the variable speed drive,” Anderson says. “Also, remember that the pressure switch option includes a cycle control valve which greatly helps reduce the size of the pressure tank needed for the system to function.”

See the images above. They show galvanized steel and PVC H2O units. Both have a mounting plate attached to the well cap lid at the top of the unit which is above ground as most states require well casing extend at least 12 inches above the ground. The mounting plate is used to attach whatever variable speed drive control is used. It all then fits down inside the top of the casing, whether it is galvanized steel or PVC.

Anderson has another design relating to the installation. In it, a mounting bracket is included for a pressure switch that sits below the surge tank and all the fittings and tubing to connect the pressure switch to the piping connected to the tank.

This method doesn’t use a variable speed drive, so there is no mounting plate. This allows a standard pressure switch-type control to turn the pump on and off without the need for a separate drive controller.

It also includes a pressure control/cycle reducing valve installed
below the inlet to the pitless adapter that is part of the control unit.

Other units feature a mounting bracket for a pressure switch (top) that sits below the surge tank and all the fittings and tubing. Images courtesy Anderson, Merrill.

Anderson says this extra valve prevents the system from short cycling and allows the use of a standard pressure switch at a much lower cost than the control unit and the variable speed drive together.

The pressure control/cycle reducing valve makes this option much easier to use on a traditional system with a pressure switch.

This type of design is also beneficial in a setting where the homeowner or end user prefers the installation of the controls be outside near the well instead of inside a building or well house.

The self-containment of the unit allows the installer to access the unit in the future without the need for the well owner to be on site.

Both configurations are beneficial, and the application depends upon the installer and the needs of the system.

The upside is these designs give both the installer and the end user flexibility to make changes to the system, depending upon performance or changes in system needs. These can even include the desire to add a VFD as most VFDs will work with the configuration.

There are many climate benefits to the design, especially in cold weather where freezing pressure tanks and controls can be problematic.

In southern locations that use a shallower bury depth, at least 3 feet is needed as a bury depth. If this is an issue, Anderson suggests pump professionals install the system with a lower discharge from the well.

“Even in southern locations with a shallow water line bury depth, installers would want to move the discharge line to 3 feet below ground level so all controls can fit inside,” he says. “The maximum depth has been in the 7-feet to 8-feet range. Anything deeper would require a specialty order.”


The units are widely accepted in nearly every state. Merrill is seeking approval for the use of the units in Minnesota, Wisconsin, and Michigan. The economy of installation, variability of design, and convenience of controls make them an alternative approach for any groundwater professional.

Lana McGee Straub, RL, has written for WWJ for more than 15 years and reported for several national publications, including the Washington Post and NPR. She has an MLS in oil, gas, and energy law from the University of Oklahoma College of Law and is a ROW agent. She has worked in the groundwater industry for more than 20 years as the operations manager for Straub Corp. in Stanton, Texas.