Have a 7 year old well (about 220 feet) deep. For the past month I have had very dirty water... never have before... and there has not been any extremely heavy rain. I have a spring fed lake near my home and well... and the well, home and lake are situated near a moderate runoff from a 40 acre field (not in use for the past 7 years). We've never had any sight of dirty water or any problems before. Should I have been doing something all these years? We don't drink the water and use bottled water for cooking, but my toilets and wash are very dingy and dirty. The cold water has always smelled but I thought that was part of living with well water. Will this problem work its way out or should I take some sort of action? Perhaps a shift in the ground caused this? It's been a month since this started.

At 220 feet it is unlikely that your well is being contaminated by surface water unless you have a crack in the well casing or the well head is below the surface of the ground or you have a pitless adapter and the seal is leaking.

A crack in the well casing is highly unlikely particularly if properly grouted. Not logical that you would have a crack after 7 years. If well head is below ground check to see is cap is properly sealed and that surface water cannot pool up around it.

Where is tank relative to the well? If the tank is remote from well and there is a check valve on the well line before the tank it is possible that you have a ruptured well line.

The logic for that assessment is, if you have a check valve on the well line at the tank and you have a ruptured line, when the pump shuts off, water in the line will drain back down the well because air, surface water and soil can drawn into the line through the rupture. When the pump comes on again that contaminated water is pumped into the tank.
Suggest opening several faucets and let run long enough to empty and flush all the water from the tank. The water should clear up after a period.

If it does, I suggest cutting the line at the well head and see if you are pumping contaminated water from the well. Assuming that you do not, install a check valve at the well head. If you have a ruptured line between the well and the tank that check valve will prevent contaminated water and soil from being pulled into the line and down the well. You will still have the leak when the pump is running.

If the quality of the water improves, you can then begin looking for the ruptured pipe.

Is this a submersible pump we're talking about?

If you have a ruptured wellpipe with a sub pump, you should notice a lot of air in your water. This is because, as the water drains out of the wellpipe, air takes its place. When the pump cuts on, the air is pumped into the tank.

Something would seem to be draining water into the well down the sides of the well. This would introduce dirt into the well water. Might have been a temporary occurrence. Try running your water through an outside faucet for an hour or so and see if you can get the dirty water pumped out. If it happens again after that, then you know something is washing water down the sides of the of well.

Is there a cover over the well? How far does the pipe run from the wellhead to the tank? How deep?

Yes, the pump is in the bottom in the bottom of the well. It is covered and we have it secured. I'll run the outside faucet today. The drillers had to go down about 220 feet to put the well in (if that is your question).

One more question. Your pressure tank... is it a bladder tank or a galvanized tank?