As I wrote in my last column, the pitless adapter is a rather simple but important device used to complete a modern well. All of these have a way of keeping pumped water below the freezing point or frost line. They also have a way to, in effect, make or break this below frost line connection to the service line that takes the water to its next stop on a trip from the aquifer to the faucet or whatever use it fills.
The first pitless adapter that I saw in the mid to late 1950s used a spool as the sealing mechanism about 5 feet below the ground — at least here in southern Michigan. I understand in some parts of the country these spools or connecting points from the inside of the well to outside the well have to be as much as 7 or 8 feet deep due to extreme frost. Likewise, in milder climates a 2- or 3-foot depth will work just fine. In any event, whatever the depth, the spool is equipped with at least two and sometimes four O rings. Each O ring fits nicely into a machined base and keeps the water under pressure between itself and the other O ring. This machined base is something like a large diameter pipe tee with no threads on the “run” and a threaded joint on the “branch” that connects to the service line. I understand that some really early pitlesses used cup leathers in place of the O rings, but I never saw one of these. I have been told that they could be very difficult to use when breaking the waterproof joint for service to the well, pump or drop pipe.