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How to dig a water well:
This article and references we include describe the process of digging a well to provide usable water and the steps taken to make the well safe and sanitary. We include both technical advice and a description of the practical problems that one must encounter and overcome in providing usable water in an area where public water supply is absent or limited.
This article series offers advice for Hand Dug Water Wells and the sanitation and maintenance concerns with this water supply type.
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Alvin Starkman M.A., LL.B., Casa Machaya, Oaxaca Bed and Breakfast.
This article series offers advice for Hand Dug Water Wells and the sanitation and maintenance concerns with this water supply type.This article describes the process of digging a well to provide usable water and the steps taken to make the well safe and sanitary. We include both technical advice and a description of the practical problems that one must encounter and overcome in providing usable water in an area where public water supply is absent or limited.
[Click to enlarge any image]
The article author, Alan Starkman is a retired Toronto attorney who operates the Casa Machaya bed and breakfast in Oaxaca Mexico.
Mr. Starkman has written more than 90 articles about life and cultural traditions in Oaxaca, Mexico, and writes here about well digging from a lay person's perspective.
Watch out: before attempting to construct a hand dug water well, see Building a Hand Dug Well - SAFETY
Water in Oaxaca as a Motivator for a Well Digging Project
Americans and Canadians will eventually come to consider water as a resource of finite supply. In Southern Mexico we have already come to this realization. It’s been predicted that the scarcity of water in Oaxaca will worsen over time, as a result of climate change and other factors. The past fifteen years have borne witness.
Our photo (above left) shows our dug well nearing completion, with well piping and wiring being configured. Other images throughout this article series demonstrate the process of digging and equipping a dug well to provide a useful water supply.
To receive water, Oaxacans rely on a municipal water delivery system, supplemented by water trucks (known as pipas). Supply via the former has been met with a reduction in quantity, quality, and frequency of delivery. The implication is that as the dry season approaches one cannot rely on the delivery of reasonably clean water when it’s needed.
The situation is worse for residents without cisterns, who must fill small tanks (known as tinacos) of roughly 1,100 to 2,500 liters, or makeshift receptacles such as old stationary propane tanks.
The fortunate among us have cisterns with a capacity of anywhere from 5,000 to 25,000 liters. Commercial enterprise cannot rely on the municipal system for their needs, and must order pipas on a regular basis.
Toward the end of the dry season when water does come into our cisterns and tinacos, sometimes it’s so dirty that residents elect to shut off the valve by the street in favor of purchasing water from pipas. [Water storage tank or tank truck. Literally, pipes.]
Pipas come in sizes ranging from about 1,100 to 20,000 liters. During the dry season it’s sometimes difficult to get a pipa to the house, especially for residences in the countryside or up steep hills. And of course the cost of a pipa is greater at this time of year. One is paying for the driver, truck and fuel, as much as for the water itself. Accordingly, those with small cisterns or only a tinaco end up paying up to threefold more per liter, than those with larger capacity tanks.
In the face of this progressively worsening water problem, many residents who think they may be above a water table that is not prohibitively low, are electing to investigate the feasibility of digging or drilling a well, if not for the present, then as a precaution and investment for the future.
Drinking water is distinct from municipal and pipa water. Tap water is used only for washrooms, kitchen sinks, doing laundry, and lawns and gardens. Water for drinking and often cooking is purchased at the store or from water trucks selling five gallon (19 liter) jugs.
The Decision to Dig a Well in Colonia Loma Linda, Oaxaca
Moving to Southern Mexico presents a learning curve – in fact several challenges. Even more so when it comes to an urban middle class Canadian couple trying to appreciate the minutiae involved in deciding upon and then proceeding with a well digging project:
In retrospect it’s easy enough to enumerate the foregoing list, which is far from exhaustive. But its compilation was a work in progress, with issues and decisions to be made arising periodically over the course of three years. There is no course for Oaxacans wanting a well.
Details are at Choosing Dug Well Location & Method. Excerpts below.
Our home in Colonia Loma Linda is at the top of a hill facing the street, Calle Sierra Nevada. The lot extends to the bottom of the hill, where there’s a predominantly unpaved dirt road which during the rainy season appears more of a stream.
Our photo of our dug well (near completion, at left) shows just how steep the hillside is.
There are tell-tale signs of moisture near the bottom of our hill: trees remain green year round, a bit of river reed (carriso) grows near the bottom of our land; a neighbor has healthy banana trees; and he and another neighbor have wells. Our own fruit trees, further up our hill, have traditionally struggled, I assume in part because of the distance to the water table, and of course because of the stone substratum.
Below perhaps a foot of hard earth, our land is pure rock. We knew this when we bought it, and were able to confirm it as we watched workers digging three retaining walls for the house, by hand, excavating several feet down.
Let the Well Digging Begin in Loma Linda, Oaxaca - Details are at Beginning the Well Digging Process. Excerpts below.
Shortly after we had moved to Oaxaca, I went to a rare contents sale with a friend, and amongst other things purchased a job lot of nails, chisels, hammers and mallets, figuring that in the course of the balance of my lifetime, some of it would be useful. I had already learned to be much handier around the house than I had been the previous 53 years. Now I had more of the supplies that I used to come across in my father’s garage.
Rogelio, in consultation with the well digger, comprised a list of materials for me to acquire: ropes, a longer ladder, and buckets. I already had the mallets, and it was just a matter of finding an ironworker (herrero) with the machinery necessary to forge points and flat surfaces on the chisels. I had wrongly assumed that every herrero possessed all such equipment.
Our photo (left) shows at upper center the brick arch that marks the final location selected for our dug well. You can see that this well had to be dug on a steep hillside, and down-hill from the buildings and most of the property where its water would be used.
Digging of our "dug" well began in January, 2008.
I instructed: “Start digging here, where those couple of rocks are lying on the ground; not over there, not over there, it has to be right here, because that’s what the diviner said. Ensure that the diameter all the way down is at least ten centimeters wider than the outside diameter of those rings over there. We have to be able to lower them down.”
To Every Time, There is a Season: A Season to Dig, A Season to Suspend
Details are at Suspension of Well Digging - Wet Season. Excerpts below.
In order to get a true reading of the volume of water one can expect to extract from a well, at the worst of times, the digging should proceed and certainly conclude as close to the end of the dry season as possible.
That’s when the water table is the lowest. Digging during the rainy season is more difficult (though the ground is softer), and certainly concluding the digging during or after the rainy season does not provide an accurate measure of the water one can expect to be able to obtain from the well when times are tough – very dry.
We had become both jaded, and admittedly a bit lax about the whole thing, nevertheless feeling a greater sense of urgency as the months passed. Media reports and advisories from ADOSAPACO, the water commission, contributed to our increasing anxiety.
Details are at Use or Omit Pre-Cast Well Rings. Excerpts are below.
At the very end of our well digging process we saw a problem: when we were using heavy machinery to deal with a fence issue (the debris from digging the well was so heavy and plentiful, that when the rainy season began it was pushed to the bottom of our hill and destroyed our fence).
When I wasn't looking, the loader operator cut away too much of our land, so now the well is dangerously close to a precipice. (Photo at left).
We had two concerns:
An inspection of the well interior as well as the surrounding terrain, and finally consulting with more experienced well diggers from the area will help assess these dangers.
Meanwhile, we took temporary steps to reduce eroding the little soil that remained: chicken wire (mallo) and posts were laid against the soil on the down-slope side, and we placed our un-used well rings (anillos) as planters at the base of the slope. It is interesting that while our well digger had to chisel through stone to construct the well, just a few feet away was loose soil on the hillside. Don't assume that rock formations or shale extend uniformly through the soil.
Details are at Deciding When a Well is Deep Enough. Excerpts are just below.
Fermín lived up to billing, in short order digging down to over 11 meters. [In the U.S. and Canada most dug wells stop at about 10 meters or around 30 feet deep.]
It took over an hour every morning to pump out the water from the night before. Then Fermín disappeared. He just didn’t show up one Monday morning, and didn’t answer his cellular for a few days. Eventually he did respond, and advised that he’d return in two weeks. Five weeks later he was back, advising that we’d probably have to go another three meters down.
After three or four days of digging, Fermín told me that he would not be returning. He said that it was now taking him about two hours in the morning to pump out the water before he could begin digging, and that there was about five meters of water to be removed.
Our well photo (left) shows the rocky sides thorough which Fermín had been chiseling.
To Fermín that signified that the well would produce sufficient water for our requirements and that there was no need to dig further. To me that meant we had ourselves an honest pozero who could have continued (he didn’t have another job pending, since my friend had altered his plans regarding using Fermín in the foreseeable future), but let us know it wasn’t necessary for him to continue.
As is often the custom with trades in Oaxaca, a brief “discussion” ensured about how much we owed him (measuring his progress by lowering a stone attached to a rope to the bottom of the well, and then using a tape measure), followed by the friendly departure of Fermín & Son.
Details are at How Much Water Will a Dug Well Deliver?. Excerpts are below.
I'm at about 10 meters depth, well diameter about 1.4 meters. At 4 pm when the digger stops for the day (by hand hammering through rock with a mallet and chisel), he drains the water. At 9 am the next day the well has 1.6 meters of water in it. I intend to complete digging further into the dry season. However, based on the above data, how many liters of water can the well produce in a 24 hour period?
By way of update, the pozero returned at about 11.15 meters, and said we'd need another three meters or so. Then a week later he said he's finished, that in the morning there is 5 meters of water and it takes two hours to pump it out, so for sure we don't need more.
Our photo (left) shows a plastic water storage tank under construction in San Miguel de Allende, Mexico. Where a well flow rate is limited, water storage is often necessary to provide good water flow to the building served.
Most code compliance and health officials want to see 3-5 gallons per minute. You've got about 0.6 gpm. We would try to keep good potable water piping out of contact with other non potable piping - the concern is that events like loss of pump or pressure can back-contaminate between the two. Also, a submersible pump will be the most powerful way to lift water - depending on how high you need to raise it you might want that.
An accurate answer to th question of how much water is in a well needs to address both the static head or volume of water in a well when it is at rest and not in use (see Static Head of Water in the Well), as well as the flow rate or yield: the rate at which water flows into the well opening (see WELL YIELD DEFINITION). This is also called the well recovery rate. Together these tell us how much water is actually available from a well -the WELL QUANTITY TOTAL.
At WELL FLOW RATE we provide a detailed calculation of how much water we expect this dug well to yield, measured in gallons per day, per hour, or per minute of water flow.
Watch out: if you install a pump whose pumping rate exceeds the well yield or flow rate (see WELL YIELD DEFINITION), the pump may run dry and be damaged. The risk of pump damage is greater in a well that has a small static head (see Static Head of Water in the Well) or in conditions under which the pump is left running for long periods so that the static head is likely to be exhausted. If you have this risk or this problem on a well, see the advice on protecting pumps given at WELL PIPING TAIL PIECE.
I have to work through decisions regarding pumping directly into our 17,000 liter cistern, or first into a smaller cistern and then up to the main one (in case we can drink it with or without treatment I wouldn't want to mix it with the unsanitary municipal water), or have "Y" tubing so I can divert into a smaller cistern whenever I want OR send it directly to the main cistern, etc.
Note on pumps: for pushing water from a dug well up a steep hill to point of use, you will probably want a pump with good lift capacity, such as a submersible unit, combined with a water pressure tank or additional water storage higher on the property.
At left our sketch of a types of well water pumps is courtesy of Carson Dunlop Associates. The drawing shows the key differences between a one line jet pump, two line jet pump, and a submersible water pump.
Details are at Building a Well Arch. Excerpts are below.
Take a look at the sagging, temporary lift used by the workers to remove stone and soil as the well was being dug (below left) and you will appreciate why expert well builders like to finish the job with a more functional arch over the Dug well opening. Our masons built a temporary support scaffold over the well opening, then constructed a plywood arch against which a brick arch would be constructed.
Our photos below show the brick arch being completed over the Dug well. Once bricklayer has completed the arch (a couple of days), then he will wait a week or so take off his mold for the arc.
Next we will clean it as best we can, and then proceed. The masonry arc, being secure, will permit me to lower myself into the Dug (really "chiseled") well for an inspection. It will be the first time for me descending 12 meters into the ground
Watch out: never enter a confined space such as a dug well without proper safety precautions, including:
The brick wall we show constructed around our dug well (photo below left) serves two purposes.
Details are at Checking Dug Well Sanitation. Excerpts are below.
I had the water from our new dug well tested at a local university, but after a couple of rains and no cover on it, and it came back with some e-coli, apparently no surprise.
The engineer said to come back after the tabique circle (partition wall circle) and arc are done, the top is on, and all the crap at the bottom has been removed and the rest has had a few days to settle so we can get a more accurate readying of more or less pure water without drain-off contaminants.
She said she'd then test again, and we would put in some bleach, and test again to see the potential. She is confident that the water will be drinkable (not that we will drink it, but it certainly suggests your contention is right on that it should be kept isolated from the regular cistern water).
The best of all is that she's prepared to work with me in term of recommending chemicals, people to clean and filter, etc. I already have a pump guy for a submersible, and it's just a matter of determining how many hp, you'd think a simple task, but not so down here.
It is almost impossible to keep a dug well sanitary - dug wells are usually completely open to surface and ground water runoff.
You can shock the well, but if you are not going to drill a modern sanitary well (costly) you will need to install water treatment equipment to sanitize the water - after testing to see what contaminants besides bacteria are present. Shocking a dug well (see WELL CHLORINATION SHOCKING PROCEDURE) to try to make the water potable or safe to drink is usually pointless. If nonetheless someone insists on shocking the well, or on letting it "settle" before further testing, also see our warnings at FAILED WATER TESTS - WHEN to RE-TEST.
Our photo (left) shows a typical residential well water chlorination system.
If the well water is used for irrigation, such as watering plants, and possibly for filling a swimming pool (slowly or you'll run the well dry - see How Much Water Will our Dug Well Deliver?) - watch out whose water will be disinfected by the pool treatment equipment, using the Dug well may be fine.
But if the Dug well water is to be used for drinking - that is, for a potable water supply - water treatment equipment will be needed.
Before you can choose what water treatment system is appropriate, it is important to test the water for both sanitation issues (bacteria, chemical contaminants) as well as aesthetic concerns (sediment, odors, taste).
and WATER CONTAMINANT LEVELS & LIMITS for advice.
Watch out: don't mix water from an un-sanitary source with potable or sanitary drinking water. Doing so risks cross-contamination of the entire plumbing system. If your property includes both potable and non-potable water supplies, be sure to keep their piping and storage facilities completely isolated from one another.
Also see WATER TREATMENT EQUIPMENT CHOICES for alternative methods of assuring that water from a dug well remains sanitary and potable,
and see WATER PUMP LIFE EXPECTANCY for choices on methods for moving water from a dug well to storage tanks or to the point of use.
Readers should also review our home page for DUG WELLS, by HAND what are they, can they be sanitary and safe?
Looking Ahead to Part II of Digging a Well in Oaxaca
In my next and final installment, I deal with issues such as flow rate, biological analysis, decorative brickwork and custom iron cover, ongoing issues relating to structural integrity, and matters such as pumps and piping, the additional cistern, and whatever else it takes to conclude such an endeavor.
The links below provide the details of how to dig and construct a hand dug water well.
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