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BobMac 11-11-2009 04:08 PM

colloidal clay in well water
I had a new well drilled a few weeks ago. The driller advised me to run the water slowly continuously to clear the water. I ran the well at ~ 1 GPM for days and the well motor burned out (when I took it apart it was full of gray silt). I replaced the motor and have run the well at wide open for hours, then at 1 GPM for hours. Shut it off, started back up, etc. Sometimes the water starts to get somewhat clear, then turns black, then back to dark gray. I put some alum in a jar and it settled the gray out. I would prefer not having to install settling tanks with alum injection, etc. Would a water softener do anything with clay? Any ideas on how to clear the clay from the well? Is running wide open better than slow? Should I run it continuously or off and on? Will the clay clog the pump motor and burn it out? (Goulds pump). Thanks for any advise you have!

Daniel Holzman 11-11-2009 09:05 PM

I am not sure from your post that you actually have clay in your system. It could be silt. The difference between clay and silt is that clay is a particular type of mineral (there are many different types of minerals in the clay family), while silt refers to a particular particle size. Usually silt is very fine sand, but it could be very fine rock particles, and a few other types of materials.

The point is that silt will suspend in water, meaning it will not settle out. Most of the time, clay does not suspend in water, because it forms microscopic sheets. You can eliminate silt from your water by installing the proper size screen in your well. I am surprised your well driller did not discuss this with you. You did not discuss any details regarding the installation of the well, specifically depth, diameter, amount of open casing, type of screen, normal depth of water, chemical content of the water, or drilling technique. These could all be relevant to the problem you are having. Perhaps you can post with the specific details of your well, and we can make some progress in diagnosing the issue and offering options.

BobMac 11-12-2009 06:24 AM

After my first post I realized I should have included some more information. The well is a drilled well, 6" diameter, 220' deep, 20' casing and the pump is at 200'. The pump is a Goulds and has no special screen on it. This area has lots of clay and sulphur. The ground all around the drill site is covered with gray clay runoff. There is also a lot of shale in the ground. When I let the well settle over night the water level in the casing is about 4' down from the ground surface.

I have tried pouring the water through a coffee filter and it leaves no traces of anything (clay or silt). I have talked with people who live around here and clay seems to be the problem. From what I have been able to find on the internet clay seems to be the answer - colloidal clay. Other people have used alum in a settling tank to cause it to settle out, then flush the tank on a regular basis. I am still running the water out of the top of the well hoping it will clear up before I have to connect it to the house when temperatures get below freezing.

Yesterday I started running the pump wide open for 5 minutes, then off for 30, then on for 5, etc. I am running around 700 - 900 gallons a day through it and it is still gray and sometimes very dark gray/ black. Sulphur smell comes and goes.

What do you think? Can you suggest any home-made tests to see what works? Thanks again!

BobMac 11-16-2009 09:08 AM

colloidal clay?
I hooked up a 5 micron filter to my well and ran the water. The water came out the same as before the filter was put on - cloudy and gray. If you hold the glass jar of water up to the sunlight it looks like gray clouds swirling around in the jar. Any Ideas?


Andy CWS 11-21-2009 04:50 PM

If your water contain colloidal -anything- a typical filtration system will not work. You would need a flocculation system or a nano-membrane. Even with the nano-membrane, if the particulates are smaller than 0.01, they will still get through. This normally handles most of the problem but not all.

Colloidal problems are often caused by clay.

Andy Christensen, CWS-II

BobMac 11-24-2009 05:34 PM

Andy: thanks for the information. Seems like I need to do some type of flocculation. Do you have any sites that will give me the configuration for a system to inject something like Alum to settle the clay, flush, etc?

I have dropped a pinch of Alum into a jar of water (32 Oz.) and it does settle the clay out. If I then shake it up, the clay will re-settle. From what I have read it is a negative charges particle (clay) needing a positively charged particle to force it to settle out.

I'm new at this but willing to try just about anything.

Appreciate your input!

Andy CWS 11-25-2009 08:58 PM

I couldn't find a website that shows you equipment. I have some personal pix that I will try to send.

As water comes in, a alum pump draws solution from a tank and injects it into a retention tank. From there, the water goes into a backwashing filter. If you use a Class-A UV after this, you will need a large one-micron filter as a final clearing of the water.

In some cases, iodine is used instead of UV. This is injected prior to the retention tank giving it time to contact.

An RO is recommended for consumption water.

This water treatment is not simple but can be very effective.

Gary Slusser 11-26-2009 02:36 PM


Originally Posted by BobMac (Post 353694)
I hooked up a 5 micron filter to my well and ran the water. The water came out the same as before the filter was put on - cloudy and gray. If you hold the glass jar of water up to the sunlight it looks like gray clouds swirling around in the jar. Any Ideas?


It sounds like you have drilling 'mud', bentonite because the well wasn't developed as it should have been; by the driller.

Check into what he did to develop it and for how long. Maybe get a lab to analyze the stuff and tell you if it is bentonite. If it's bentonite, making him make it right. It's gray IIRC. You running water is supposed to clean it out but rarely does because you cant' run a large enough volume of water to pull the water level down in the well far enough. He can bail or purge the well or air lift it.

WELL DRILLING: Drilling mud, or drilling gel, is a major component in the well drilling process. Drilling mud is crucial in the extraction of drill cuttings during the drilling process. Bentonite, when mixed with water, forms a fluid (or slurry) that is pumped through the drill stem, and out through the drill bit. The bentonite extracts the drill cuttings from around the bit, which are then floated to the surface. The drilling mud, or gel, also serves to cool and lubricate the drill bit as well as seal the drill hole against seepage and to prevent wall cave-ins.

BobMac 11-29-2009 08:17 AM

I have actually drawn the well down to where it's out of water a couple of times. I still go through the transparent, gray and dark gray/black non-transparent stages. If it sits overnight a gray silt will settle to the bottom of the jar. The silt does not easily wash off the bottom of the jar. The driller pretty much drilled the hole, blew air through it to purge it and then left. The ground all around the well is covered with gray clay that hasn't gone away even after several hard rains. I am presently drawing household water from a lake, but it is going to get too cold to continue that and at that point I have to start using this well. I am drawing the well water directly out of the well and into the lake - not through the house, so I can pump at ~ 10 gallons a minute. I've been running as much as 1800 gallons a day and still have the same cloudy water. If I swirl the water and hold the jar up to sunlight I see clouds swirling around in the water. The clouds go from very light gray to very dark gray as I draw the water. I also get small black particles sometimes which I believe is shale. Any suggestions?

Gary Slusser 11-29-2009 01:13 PM

Sounds and acts like drilling mud to me. The gray stuff on the ground is drilling cuttings and probably bentonite, not clay.

You keep pulling the well down, you can cause other problems, kike the black particles you're seeing. IMO you need to talk to the well driller and and have him develop the well.

Daniel Holzman 11-29-2009 02:47 PM

Gary, I don't quite follow your final post. You say "The gray stuff on the ground is drilling cuttings and probably bentonite, not clay". Bentonite is a particular type of clay, mined originally in Benton, Wyoming. The OPS seems to have suspended clay or silt in his water, I don't understand how you are so certain that the clay or silt is not naturally occurring, but rather is from the drilling mud. Certainly a chemical analysis would reveal the exact type of clay in the water, which would probably answer the question of whether it was natural or was from the drilling mud, but in the absence of such a test, it could be naturally occurring.

BobMac 11-29-2009 04:37 PM

After running significant amounts of water for almost a month I'm inclined to think the clay is natural. The whole well hole is through shale and from what I understand there is a lot of clay between the layers of shale. I suspect that since my recovery is about 1.5 to 2 GPM that the veins are not flushing themselves out when I draw down but are just slowly running in. I have thought about agitating the water in the well hoping to flush the veins, like plunging a toilet. ?? What do you think about that idea? I still have about a week to "play" before I have to hook up to the house because it will be too cold to draw from the lake.

I appreciate your input! Thanks!

Gary Slusser 11-30-2009 04:11 PM

Yes Dan Bentonite is a type of clay. It is used as a drill lubricant but more so to keep the sides of the hole from falling in as it is being drilled with rotary drilling rigs.

Developing a well is agitation like you say a toilet plunger does, it washes the Bentonite out of the seams and off the walls of the well. The driller uses a bailer or air lifts the water and then dumps it back down the hole, to agitate it.

Bob, drillers today are not the craftsmen of years gone by, they have much more expensive equipment, they are in very tough competition, and usually do very little developing due to quoting very low prices which don't allow for many hours or days worth to develop a well. So they tell their customer to run water until it clears. And some never clears because there isn't enough water run gpm wise and there is no agitation. So at best, the seams are cleared with recovery water flow but nowhere between the seams.

All that doesn't mean there is no natural clay or that it isn't the cause, but it is much more likely drilling mud If the development of the well was done as it usually is today. A $300-$450 camera inspection probably would show which is which.

BobMac 11-30-2009 04:33 PM

I talked to a local well water treatment guy today. He confirmed the problem locally with collodial clay. Pretty much his recommendation is to install the usual system consisting of an injection, settling tank and filter. I understand the principle here, but was hoping to find a less space/$$ involved system. I asked about the water softener. My understanding is that the clay is negatively charged and the softener is positively charged. Seems it should attract the neg. clay?? I'm only a week +/- from "have to do it." He also suggested just hooking up and seeing what it does when only used in the usual amount a house would use rather than the 1,500 - 2,000 gallons per day I have been running. He said if it hasn't cleared by now it probably won't. What do you think?

Again, thanks!

Gary Slusser 11-30-2009 05:54 PM

I would talk to the well driller as I've suggested 2-3 times, and have him tell me what he did to develop the well.

Treating colloidal clay is not easy and from what I hear, not always successful. I'd want to rent the equipment for a month to see if it did the job. Actually, colloidal clay won't settle, it stays in solution, so the equipment will be using a coagulant.

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