September 11, 2016, a day that will live in infamy as the first time this happened:

At the time, after talking with the builder, we thought the problem was that I'd used too much of the water in the well and had drained it down to the sediment.
And then it happened again in December. But we'd had a bunch of guests. And we all took showers the same morning. So we figured we'd run the well down again.
And then it happened in January, on a day when we had hardly used any water. After that, we talked to the builder again, and he talked to the well people, and they all said we need to install tanks that will hold hundreds of gallons of water; this will take the "stress" off the well since the well pump won't have to run as often - we'll just use the water in the tanks. How the water gets into the tanks without running the well pump and stressing the well is beyond my ability to comprehend. Plus, if any of the bad water got into the tank, it would contaminate the whole thing... all 200 or 400 gallons. Right?
/handwaving
And then it happened again in February. And we called the builder and he asked for a sample of the water. He had it tested and the answer was : Iron! We have iron in our water. OK. Get a filter! That works for some kinds of iron contamination, but not all.
And then it happened this Sunday. And we called the builder and he was all about the tanks again. So we called a water filtration company and they came out and tested the water. They didn't find any iron, because the iron comes in spurts. Something happens in the well and suddenly the water around the pump is contaminated with iron. Then, after a day or so, the iron slowly settles out and the water is clear again.
They found high levels of tannins, which suggests surface water contamination. Which shouldn't happen because wells have liners that go down a certain number of feet to prevent surface water from getting in (the pump itself is 300 feet down). This suggests a broken well casing. This could also explain the iron - clumps of iron-eating bacteria and the iron-rich dirt they live in occasionally fall into the well and turn the water into brown poison until they settle out.
And then it happened again this morning.
So now we have to drop a camera into the well and see if there's any obvious problems with the casing. If there is, we have to try to get the well people to fix it. Nobody thinks we're likely to succeed at that.
And, we still have to install a filter.
Until then, we have to use bottled water.
This is country life.