Is it harmful to pump excessively out of a silty well?

[SuperGreg]

Hello all, we moved into a house a few years ago on a well. I've spent the last few years learning a lot about wells in general but also the quirks of this particular one.

If no water has been used in a while, the water pumping out of the well is cloudy. You can hardly tell if it's coming out of a hose, but fill a bucket and it's obvious, you can't see the bottom. However, if you run the pump continuously for a while (watering the garden, pressure washing, etc) all of a sudden the water pumping out looks like chocolate milk. You can see it transition in the spin down filter.

I have tried to limit water usage for anything that might cause the pump to run long enough to start pulling in the real dirty water, but sometimes it is hard to avoid. We just had the house painted and the painters were pressure washing and ran the water until it wasn't flowing through the filters fast enough to keep up and I couldn't bypass because the raw water was so muddy.

Recently I redid the entire filtration system, and added a pH neutralizer, iron filter, and carbon filter. These all required backwashing and rinsing to get ready, and in trying to get everything ready I used a *lot* of water and started pulling up the muddy water for quite some time. I finally gave up and came back to it the next day.

I've noticed that the raw water (again looking at the spin down filter) seems to be clearer than usual now. So my question is, would it help to run the pump for a while to clean the well out, or is this harmful and something I should avoid?

I know that everyone is going to suggest drilling a new well. That would be great, except for the cost and the chances that the new well will have the same problems. Here is the material in the ground described by the well report:

0 - 3 ft Brown topsoil
3 - 7 ft Brown silt
7 - 78 ft Gray silt w/some gravel
78 - 82 ft Fine gravel
82 - 84 ft Gray clay

If drilling a new well, would it be worth it to have them try to keep drilling deeper into a cleaner material? I've talked to a couple well guys and they both said the location I'm at is very problematic. The neighbor is on a surface well, and just had a well drilled and didn't hit water.

 

[Reach4]

I think it is normal to run the well continuously for a time, as long as the well does not go dry. This seems to be called "developing the well". I don't know how many hours would be appropriate. I am not a pro.

Bypass the filtering. Maybe use the drain valve that is there to drain your pressure tank, presuming that you don't have a spigot before that.

 

[Sponsor]

 

[Valveman]

I wouldn't pump it through the system. I would cut the pipe at the well and pump it straight out the main pipe. You might be able to draw enough volume this way to clean up the well. It may take hours or days. You might have to turn the pump off, let the well recover for a while, and pump it again, doing this over and over until it cleans up. And it might not ever stop making sand.

Looking at your drilling record that well should be cased to the bottom. So it could have a fine screen in the water bearing formation and a really small gravel pack around the screen, This makes a media filter out of the well much like a sand filter on a swimming pool, and the well will not make sediment. A well that makes good clean water is worth its volume in gold.

 

[LLigetfa]

What you have we call a mud well in these parts. I have a mud well. Mine has no screen, just the open end of the casing a foot above bedrock. The driller did not develop it, only pumped it for a few days at 5 GPM to satisfy the AHJ to get a building permit.

After I built the house and moved in, I installed a 10 GPM pump but the well was only tested to 5 GPM so the extra flow motivated the silt. Had lots of silt even to the point of locking the pump rotor several times. I pulled the pump and had the driller drop a few thousand gallons down into the well to push the silt back into the aquifer. I then flow limited the pump to keep the silt from being motivated but the silt continued for years and wore out the pump.

I then decided to try to develop the well when the driller declined to come out. I baled the mud out by hand and then used my old worn pump to draw as much water as the well could make which was not enough to keep up to the pump. The pump was discharging directly to a ditch through a wide open 1 inch ball valve. As I needed to move more water than the well could make, I recirculated some of the water back down the casing so the pump could keep running. After doing that for a while, the well production increased to where the pump could no longer pump it dry. I think by that point the pump was pretty well worn out but I was not going to torture my new pump to keep developing.

I set the new pump, hooked it up to the house, and flow rate limited it to keep the mud from moving. I now get about a teaspoon or two of sand in my banjo filter in a year. Any fine silt that makes it through the 100 mesh filter settles out in my HP tank or gets trapped by the iron filter and then backwashed.

Most of my neighbors opted to drill deeper into bedrock.

 

[SuperGreg]

Interesting! I am told that a well can be blown out with compressed air to remove accumulated silt at the bottom, I'm wondering if that would help in a similar fashion or if more silt would just get pulled back in.

 

[Reach4]

Interesting! I am told that a well can be blown out with compressed air to remove accumulated silt at the bottom, I'm wondering if that would help in a similar fashion or if more silt would just get pulled back in.

Hard to predict.

To remove sediment from the bottom, you can use an air lift pump and a smaller compressor. This takes longer, but is useful to the homeowner. Searching will show some nice descriptions, examples, and videos. The air lift pump requires a fair amount of water to be higher than the pumping level. Your search term for that aspect is "submergence ratio".

To blow out sediment and water like a geyser, you want a big compressor, such as 175 CFM. That is faster and more impressive, but it take renting a big diesel or gasoline compressor.

 

[SuperGreg]

Ah, yes I would have a well guy do it if it came to that.

 

[Texas Wellman]

As a licensed water well driller I'm of the opinion there is no such thing as a mud well. There is, however, such a thing as an improperly constructed Well.

 

[SuperGreg]

Well guy just came over, quoted $2500 to pull the pump and clean the well, and wants to put in a new pump if he's going to all that trouble. He did look at my well report and pointed out no screen was installed at the bottom.