We have a 50 year old well with an 8" steel casing. Depth is 100'. Static water level is 77' below the well head. Pump output is normally 8 -9 GPM into a 5000 Gal reserve tank. Water is gravity fed to 14 Cabins.

Over the last year or so, I have noticed a rusty looking sediment being trapped in every filter I have on the system, including the cartridge filters on the line coming into my home. Recently, the amount of this stuff has increased exponentially. The pump output volume has decreased to as low as 3 GPM. the pump surges a lot. I got on to the idea it was iron bacteria when talking with a driller about doing a brush and bail. His opinion was to either put a liner in the old well or drill a new well.

Recognizing there is limited detailed here, I'd like to get some opinions regarding remedial actions possible and preventive actions for future reference. I've heard everything from chlorine shock to metered chlorine injection (into the well water column to putting a silver bullet inside the well.

BTW.... I've already tried the chlorine shock treatment. Set the chlorine concentration at 10 ppm and let it sit for about 10 hours. Pumped the water out until no chlorine was detected. Seemed to help a little, but still getting a lot of particulates in the water. Some of it is black now. This process appears to have loosened up the material because I'm getting a significant amount of variation in the water flow. My best guess is larger pieces block the intake screens on the pump.

Appreciate any input/guidance from the guys with experience in this area.