After 3 years of service I noticed the water volume starting to drop off at the sprinklers. At the start of each year we would have less water and no amount of pumping would make it better. I began to suspect the sandpoint
at the bottom of the well was filling with silt. The standard way to fix this is to pull the well out of the ground or drive down a new one. I wanted to see if I could figure out how to save the unit while it is still in the ground. This is an attempt to do something "they cay can't be done"...and it worked. We have a lot of very fine glacial silt down there. Now while the pump is working it gets sucked up and blasted through the system. However each time the pump stops it will start to settle out. In the piping hoses and pump the water moves fast enough to stir it up again and clear it, but not at the bottom of the well. Down there it has a chance to settle out of the water column and pack hard. Soon my 24 inch long sandpoint was only 20, then 16, then 12... I could still get water but the pump was working hard, recharge times were way up and it would only run one sprinkler at a time instead of two. Now I have a 24 inch sandpoint again and I can run a pair of sprinklers just fine again.
A NOTE ON THE VINEGAR
I open up the video by pouring vinegar. Now this isn't what was wrong with my well but if yours has been working faithfully for decades then ever so slowly dropping off vinegar might work for you. Especially if you build a lot of lime scale. Please don't use anything nasty like Limeaway or similar. Sure it might work better but you DO not want that in water you drink. Simple wine vinegar is drinkable, nasty straight from the bottle sure, but drinkable. Stick with what is 100% safe when groundwater is concerned.
Anyway if scale is blocking your sandpoint screen try my vinegar trick but remember:
1. It will eat the pipes to some extent so don't let it sit in there for a few months.
2. Chill it. As close to the freezing point as you can. It will help the vinegar sink to the bottom faster/more concentrated.
3. Don't skimp. I have a shallow well and I sort of knew scale wasn't my trouble. I was just demonstrating. If I had a deeper well or if I knew scale was an issue then I would have dumped four or five times as much down there and let it sit for a few days.
If you don't have a large air compressor you can rent one.