I have spent a lot of time searching online and found this forum to be among the best at providing answers to questions without fussing about "search the forum first". I have searched forums and cannot seem to see any situations that directly correspond to mine, but that may be a failure of my searching abilities. I'll describe it and please let me know what you think.
We live just outside Houston, and have a well which is our single-family home water supply. It was drilled in 2007 during construction of the home. The well is 353 ft. deep, submersible pump, sand formation. Per the driller's report, depth to water was 78 ft. below surface, pump bowl was 160 ft. deep.
Problem description - We have noticed from the beginning that the water quality was not "pristine". The initial conditions we observed were a slight sulfurous / rotten egg smell (H2S) which we had been previously warned about for wells in our area, as well as a slight amount of sediment. We consulted with the well driller and he assured me that if we flushed the well for a couple of days it would "clear up"... but it didn't. We filled a 40,000 gallon swimming pool and water quality never changed appreciably.
I installed a whole-home sediment filter and a fine-particle carbon filter after it. These are both off-the-shelf items from Lowe's (Whirlpool brand). The carbon cartridge completely eliminated the odor, and we couldn't detect any sediment in the house. The fill line for the swimming pool was taken directly after the well tank, and we could still smell the odor when adding water to the pool. There was also a noticeable tint of gray in the water to the house. This was most easily observed in our bath tub, which is white porcelain. It takes a large volume of water to realize that it isn't crystal clear, and it is not easily observed in any clear glassware. It could also occasionally be observed as a black residue on the toilet bowls where the water sits (not a ring, but a light patchy discoloration of the part of the bowl which is submerged).
Immediately prior to move-in, our driller chlorinated the well. Right after moving in, we had tests done on the water, to assure that it was sanitary (Coli-form bacteria and HPC). We also had samples tested for hardness (and used our pool testing equipment as well), and they confirmed our observations that the water was not "hard" because soap lathers quite easily. Have lab results but cannot find them at the moment. The well driller's report also states the water as "soft". We have not had the water tested since the first year. We chlorinated the well once more about one year after move-in, and have not had any concerns about the water from a health standpoint (i.e. no illnesses that we might tie back to bad water).
For lack of any other cause, I can only surmise that the Texas drought of 2011 seems to have brought about a change in our water quality. We have noticed that the sulfurous odor appears to be gone, and in its place I now detect a "bicarbonate" smell (for lack of a better description). The water straight out of the well is fizzy (not soda-pop foamy, but definitely some sort of dissolved gas). It has a faint but distinct odor which is not unpleasant, but definitely not what I would call "normal". We found over this past summer that we were getting reddish-brown solids coming out of our hot water heater, which gunked up our washing machine and bath tub. I flushed the tanks of the water heaters, which was the first time it had been done since we moved into the house.
We are now seeing that the gray tint is darker, and have really come to a point that we are concerned about the safety of the water for consumption. I had recently installed cartridge filters which don't have carbon, since the odor seems to be a non-issue. After getting complaints from my wife about the appearance of the water, I just today switched back to a carbon sediment filter (25 micron) and a carbon secondary filter (2 micron). The water is still dark. It seems to be a dissolved mineral, however, when draining the tub I notice what appears to be fine particles left behind. They remind me of the material I observe left on the sandpaper when wet-sanding the steel axles on my sons' pinewood derby cars... so if it's smaller than 2 micron, I don't know how to filter it out.
Any advice on possible solutions would be greatly appreciated. I do plan on calling a water treating specialist, but I fear getting a hard-sell on a water softener just because those guys only have one trick up their sleeves.