Well houses provide protection for the pump apparatus of your water supply. In addition to that, they can add a pleasing feature to the landscape and offer function beyond just housing the pump. The crucial element in designing the structure is the fact that sometimes the well piping must be lifted from the shaft for repair. Therefore, small structures are generally built so that the roof comes off for just such a purpose. If you would like your well house to also function as, say, a garden shed, then the placement of the building around the well is critical. If your well pipe is PVC, it will bend enough to get the pipe out of a door. If your pipe is galvanized metal, it will not bend and will have to go straight up. Keep these things in mind when making your plan. Another option is to place the shed portion of the building over the pressure tank and gauges, yet have the pump pipe outside of its confines, where it can be covered with a much smaller, removable structure.
Consult local building codes as to foundation requirements. Determine the size you want the well house to be. It must be tall enough to contain the pressure tank and wide enough for a person to get into it to make repairs. Mark off the dimensions on the ground with string and stakes. In this application, the roof will remove for ease in reaching the pump.
Dig foundation according to local building codes. In some regions, the codes may require you to dig below the frost level (24 inches or more). Lay concrete block up to the height you want the floor. The top course of block would be a step block. (A step block is a notched block.)
Pour concrete inside the perimeter of the foundation blocks, level to the top of the step blocks. The well casing should protrude 6 to 12 inches above the floor. After the concrete is poured, install anchor bolts. Let cure.
Drill holes in the 2x4s at the position of the anchor bolts. Place the 2x4s around the perimeter of the concrete on the anchor bolts, leaving a 36-inch opening for a door. Secure the wood with washers and nuts. The bottom plate is complete.
Frame in the side walls with 2x4s using standard construction techniques.
Cut 2x4s to fit on the top perimeter of the sides frame. This will give you two thicknesses of horizontal wood. Do not attach. Set aside. Install plywood siding, clapboard or board and batten to the framework.
Cut rafters according to the size of the structure. Attach rafters to the 2x4s set aside in Step 6. This will be the bottom plate of the removable roof.
Cut plywood to fit rafters, allowing ½- to 1-inch overhang. Fasten plywood to rafters. Cover with tar paper and shingles or other roofing material.
Set roof unit atop structure. The weight of the roof will hold it in place.
Construct a door from plywood siding. Hinge it in place. Attach handle.
Paint or stain as desired.