Using Compressed Air to Push Water from a Well

Guest,

I don't know much about water wells either but when mine was put in I did pay attention to a few things. First of all the casing (I was told) only goes down 20 to 50 feet. Once it's into bedrock there's no more need for it and the more you need the more expensive it becomes.

Around here wells are often 'fractured' (a process of introducing high presure air to literally fracture the rock) to revitalize them but it's a dangerous process and should be left to a professional. It's possible to ruin it if done improperly.

Don't you think the air pressure might push the water in all directions, including lower in the ground?

No, the air forms a bubble which pushes the water above the bottom of the air pipe to the top.

Hello Guest,

You do not list your Location or Country, so the following can only be advice in general.

Artesian or bored/drilled wells have a problem in common: The water must be kept flowing regularly, or the well flow will become lessened and eventually cease.

Remember that the suction pipe does not go into a huge underground lake, but a small cavity/void which fills up with water leached or flowing through cracked rocks or sand.

Your "good idea" of using compressed air will not work, because that would prevent water ingress to the small void at the well suction pipe end, and by driving back silt into the rock pores or sand, thus choking off the water flow into the void, your well would become 'dry'.

I do appreciate your silt problem, and deepwell pumps for such a well as yours, need to have a spare pump ready, to drop down inside the casing, after withdrawal of the pump with the worn impellers.

The withdrawn pump is immediately repaired, and kept as the spare, for the next pump changeover.

After a few changeover operations of that nature, you will have a recorded basis for the regular changeover of the deepwell pumps.

You say the "water is silty", and that silt has to come from somewhere = the strata level of the aquifer your well is drawing water from.

If you plan on using that well system for many years, it may be cheaper to fit a stainless steel strainer/screen on the pump intake, and carefully check the pump condition at regular intervals, removing the silt as necessary at time of lower water flow, which indicates the bottom strainer is becoming clogged.

You don't say what the silt consists of, it may be an old clay pan or old riverbed which the underground small void from which you are extracting the water.

Cost wise, you need to weigh up all the local factors.

It may be prudent to drill the well deeper, into a different strata, one which is below the silt zone.

Your local well-drillers would be able to advise you on that.

Silty water which arrives at the well-head, may have the silt separated by 'settling pond', centrifugal method, or filter.

If you use a 'settling pond' ensure it is properly covered, or you may have a mosquito invasion, water snail infestation, algae growth or the water fouled by birds or animals.

Check your water:

Dependent on your location, it is important to ensure that the pumped water is safe for people, animals and irrigation.

Wells were drilled and dug by well-meaning folks, trying to help out locals in poorer countries.

In some cases: Bangladesh, Peru, the well water looked good, but was laden with toxic minerals, from the Himalayas and Andes.

Teeth of people who have ingested Arsenic with the drinking water from their new well, for example, do not look pretty at all, plus the attendant liver, kidney, nervous system, brain and other bodily damages.

Trust that assists you.

If you care to advise Location & Country of the well it may be possible to assist you further, and more completely.

Kind Regards....

Well well well the compressed air well is back.

If the casing went down until solid rock there would be no water entering the well and nothing to pump.

Unfortunately the water must drain from the surrounding area and any pressure would keep or push it back. The effect will be that the water table in the vicinity may rise a little.

The only method to use compressed air is to use an air lift pump. (I don't know if they are available anymore - and the efficiency "sucks")

Air is pumped down with a pipe and water is pump with a Venturi through a second bigger pipe.

Hello Hendrik

I had thought of the "Air Lift Pump", but discarded the idea, because there would be far more silt disturbed and lifted to the surface, and that silt is a large problem.

Air Lift Pump efficiency is rather low, especially for a water lift of the height quoted, thus the electrical requirement would be far greater for the big air compressor needed.

Aerated water would also require a settling tank at the top, before further pumping occurred, once again increasing the costs.

Kind Regards....

Hi Sparky - I agree but my point is that it would be the only way of getting water out by using air.

Long ago I had a friend who was working on a air pressure operated diaphragm pump for boreholes. I have lost contact with him but I don't think he succeeded.

Air lift is used in deep shaft sewage processing. The air introduces an upward current in the second part of the shaft. The pressure needed to do this ensures a greater rate of take-up of oxygen by the sewage in that part of the shaft, resulting in smaller plant footprint per unit of flowrate processed.

Most borehole water wells use a multi-stage centrifugal pump of small diameter suspended from the end of the borehole riser pipe. Detailed mechanical design is needed to ensure the bolts holding the upper part of the pipework together can withstand the stresses of all that pipe hanging down from them. A heritage 3in borehole riser from -500ft, for example, might use Table E or Table F flanges; Table D simply isn't up to the job.

I have been in the well business for 42 years, and have dealt with this situation often. Easiest, most efficient way to lift water, given the stated parameters:

Run 2" or 3" pipe to desired depth (340' in this case). INSIDE the eductor casing, run 3/4" air line to a depth of at least twice the static water level. Deeper is better, up to the pressure capacity of your equipment.

When you turn on the air, water will be lifted in the eductor casing, and enter from the well at the bottom. You will probably be able to develope the silt out of the well after a time. If your eductor is too deep and near the production zone, it may keep the well stirred up forever, you may need to move it up above the entry point, but still with adequate submergence. It doesn't take much air to do this, if done properly.

If you have further questions, e-mail me at rockbit8@hotmail.com

30 years ago i was intruduced to a very simple pump with pvc pipe attached to a plastic device and a hosepipe taking air to the bottom of a borehole. Do you have any information on this, and if so, is their a product on the market? Some farmers in the Eastern Cape are desparately looking for such a device

Thank you

Bartel Pieterse