Well in the last month the water which normally taste superior was now tasting yucky. I opened the shallow well and visual inspection seemed just fine. So I dumped in some chlorine and washed the walls that I could reach. Then let this rather high concentration on chlorine water reach the reservoir and sit some. The chlorine passed through in a couple weeks but the bad taste remained. Meanwhile we carried our drinking water from our neighbors.
I then uncovered the reservoir lid which is about a foot underground. A visual inspection looked rather good. The water was clear and I could see the bottom easily. There was no water leaking into the tank that I could see. But I did see some contamination, about 0.5 inches round, in the bottom which appeared to maybe be a bug or something. I got a hose working as a siphon and was able to suck this contamination out first thing. Then I went further and let the hose siphon run for 4 hours emptying 2/3 of the tank. I climbed in the tank and used a broom to scrub the reservoir walls and also stir up the maybe 1/8 inch of sand/soil on the bottom making the water very muddy. I then used the house pump along with the siphon to remove most of the rest of the reservoir water. With 1/2 inch of water remaining I used a shop vacuum to remove the remaining water along with any remaining sand/soil.
I then turned on the well pump and started the fill process. Do to the design of the system it is best to let the reservoir fill almost half way before turning on the house pump after the prime is lost. I let the reservoir fill overnight and the following noon was able to turn on the house pump which primed first time. Before I buried the reservoir again I covered the lid with some tarp material which may stop any critter from entering the tank again.
So we lost all water for well 16 hours. Linda did several loads in the washing machine the same day and also we ran the dishwasher. We expect the water to be slightly cloudy for a couple of days and hopefully when all settles out should be back to perfect soft, clear and great tasting water, again.
The cleaned reservoir.
The lid is under this section of walkway. So this is after all the digging.