How to Drill a Borehole in Zimbabwe, an Experience

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We are yet to drill a borehole at the homestead. You can read here about how our water source currently works.

However, we have been involved in borehole drilling efforts at our other piece of land in central Zimbabwe. Images in this post are from our borehole drilling experience there.

In as much as we share our experience here with all who care to tap into it, this post will also serve as our go-to guide when we eventually need to drill a borehole at our current Eastern Highlands homestead.

Since this will be a comprehensive guide, there will be a few things to understand first before we get into the finer details of drilling a borehole in Zimbabwe. It will be worth it if you want to do your borehole drilling in Zimbabwe the right way.

​Underground “Rivers”

Let’s start here. As much as the face of the earth has rivers traversing the surface, rivers which we see every day, there are also some freshwater “rivers” that flow below the surface. These underground sources get their water from rainwater as well as leaky dams and rivers flowing on the surface.

We have rivers in quotes​ in the title​ here. ​This is because ​these are not ​​rivers as we know them​ from geography class​​,​ but rather​ aquifers. Aquifers are bodies of rock and sediment which contain groundwater. ​The water is trapped in these bodies, as it were, due to an impenetrable layer of rock that can be both above and below. 

You may hear these aquifers referred to as breaks in borehole drilling speak. This means breaks in the underground rock or sediment through which water collects or flows. The illustration above demonstrates this idea.

Aquifers can be small or massive in size lasting between a few days, some weeks, a season, or even thousands of years. In technical terms, this is referred to as residence time. In this case, when borehole drilling, we are typically interested in aquifers with lengthy residence time to guarantee all-year and long-term availability of water.

Often, these underground freshwater breaks traverse the earth below the surface in all kinds of directions on any given piece of land. Any given piece of land could have four or five of these freshwater aquifers.

​It is not always obvious above ground that there is a freshwater aquifer below. For example, the picture above is of our land in central Zimbabwe. It looks dry, one ​could even say barren. ​

You would probably not believe that below what you see in the image​ above​​we sited a number of freshwater​​aquifers flowing in different directions. 

One traditional clue though​ of the presence of underground water​ is ​the presence of ​an ant-hill or churu​ on the ground surface​.​​ Ants tend to create a colony where they can access water deep underground for their survival needs. This was proven in our case where the siter confirmed underground water next to an anti-hill.

Our borehole ​drilled next to an ant hill ​yields at least 10 000 liters of water per day (of a 6-hr solar day) at a depth of 80 meters. There are​, however, at least 3 other​non-anti-hill ​sites yet to be drilled within the property promising even higher yields. The 10 000 liter yield dramatically goes up by as much as a factor of two, if the borehole pump runs continuously with expected rest times in between.

​Overall, the simple ​purpose of borehole drilling is to ​gain ​access​to ​aquifers so we can continuously draw water from them for our purposes. But first, you need to know where exactly this water resides below ground. This is done through siting, making siting an indispensable first step.

Borehole Siting

Also known as groundwater exploration or water siting, this is the first & necessary step​ when drilling a borehole​. Before you drill a borehole you must do siting which is a process of finding one ​or more ​of the underground breaks or aquifers.

As mentioned, drilling is simply a way of accessing one or many of the underground water sources so you can tap into their water and bring that water up to the surface.

There are many individuals in Zimbabwe today who are skilled at water siting. ​​The traditional water siting skill which is also known as water dowsing appears to be an intersection between art and science.

Even more, it often appears more psychic than straightforward science as the water diviner relies upon water-filled bottles, copper wires, Y-shaped tree branches, and L-shaped rods among other tools of the trade. This is radically different from the geological survey method which is more of a science accompanied with digital equipment which draws beautiful graphs on the screen and so on.

Although there are scientific ways of groundwater exploration using modern equipment which scans underground water, the best success rates are with water divining individuals who use traditional methods that have been employed for years. This is our experience.​ 

The key to an effective water siting diviner is experience and very strong references. This route is frankly not only cheaper than sophisticated geological surveys but also very fruitful. For these reasons, it is the most common method of water siting used in Zimbabwe when drilling a borehole. We recommend this type of water siting not only because it is ​cost-effective but also results oriented.​

On average, traditional water siting individuals charge between USD1​0​0 and USD200 to do your siting. For this amount or a little more they can site more than one sight within your property. You then just peg the extra sights for future use. At the right fee, water-siting individuals are often willing to travel to any part of the country including remote areas. (Read more here about water sitting).

What Does a Good Water Diviner Look Like?

A good water-siter possesses a proven track record of success in the trade. You just must get one with very strong references. In our experience, these individuals generally tend to be older people simply because of the years of experience required for one to become exceptional at the skill. 

Through this experience, the borehole siting individual would indicate to you the number of “rivers” or aquifers at your site, their flow directions, and their width.

Furthermore, a good water diviner should be able to issue you with a detailed written report indicating their findings. This typically includes the estimated depth to be drilled, estimated yield, and pump size as measured in horsepower (hp). We got exactly this type of detail when we did our borehole.

To trade on the safe side, were possible, get a siter who has previously sited for others in your area. This means the siter would have good knowledge of your area compared to a new person.

This is important, on the day of water siting, carefully peg and secure the point at which the drill must go down on the day of drilling. Shifting the drilling point or site by a few centimeters can result in a dry hole or reduced yield.

As much as borehole drilling companies in Zimbabwe could link you with a siter, they generally avoid bearing direct responsibility for siting whether through traditional or geological survey methods. This is to say, water siting is usually not part of the drilling agreement. The risk is always on you, the property owner. This is because borehole siting, in many ways, is a gamble with serious costs which the drilling contractors do not wish to bear in case of dry holes.

​Dry Holes

​A dry hole is a borehole that fails to yield any water when drilled. This can be due to a number of ​reasons​ which include poor or off-the-mark siting and failure to drill deep enough to ​i​ntercept or reach​viable underground water sources.

Dry holes are not only ​very ​disappointing but​ also​ expensive. This is because they cost the same, in drilling, just as a successful borehole. As the drilling is happening, the contractor usually extracts samples of different strata from the hole being drilled. Dry soil or stone samples with no moisture at all as shown above indicate a dry hole. Wet holes tend to produce darker and wet or muddy samples as the drilling depth increases until the water finally gashes out.

As the drilling is happening and you find that you are reaching your targeted or budgeted depth with typical dry hole strata samples, it may be wise to halt the drilling to save money.

Dry holes can also be partial. Meaning they produce water but not enough water to support your desired objective, for example, domestic use or farming.

A successful borehole drilling adventure produces enough water to satisfy the purpose of the borehole.

​How Borehole Drilling Actually Works in Zimbabwe

​Once your water siting is successfully done, the next step is to contract a drilling company to do the borehole drilling for you. These companies have a rig as shown in the image above.

A rig consists of a high-pressure hydraulic system with drill bits ​attached to a rod and ​​is ​capable of drilling holes ​into the Earth’s subsurface even through hard rock. 

There are many drilling companies in Zimbabwe today covering just about all the Provinces. The rigs are mounted on overland vehicles and are capable of accessing some of the remotest places.

​Drilling 80 to 100 meters can take as much as 6 to 8 hours. The duration of the drilling is really determined by the subsurface rock strata. Hard rock takes a lot of work for the rig to penetrate which may also proceed at a slower pace depending on the quality of the rig doing the work.

​All payments are done in cash on-site, in most cases, and certainly in our experience. The going average cost, which we also paid, was USD 1300.00 for the first 40 meters and then USD 35.00 for each additional meter.​ The additional meter amount is often negotiable depending on the total additional depth drilled.​

In our case, although we had budgeted for 80 meters maximum, once the rig arrived on site we paid USD1300.00 up-front for the first 40 meters. Our traditional siter had indicated that we would break into substantial volumes of water at about 23 meters. 

Around that depth of 23 or 25 meters, we indeed broke into our first gash which turned out to be the most substantial. However, we decided to continue drilling with the hopes of finding more breaks in order to increase our final yield.

Subsequent depths beyond the initial 40 meters were paid for every 4.6 meters. 4.6 meters is the length of each drill rod that is connected to the next one as they drill into the earth’s subsurface. It is critically important to keep track of the number of rods going into the borehole as these represent the depth of your borehole (see common tricks section below).

Depending on your location, most boreholes require more than 40 meters to yield enough water even during the wet season.​ Nonetheless, within 100 to 120 meters well-sited boreholes around Zimbabwe yield good enough freshwater volumes.​ Furthermore, cost-wise some companies offer discounts as the meters increase.

In our case of a yield of 10000 liters per day (6-hour ​solar-powered pumping ​day), we drilled up to 80 meters. However, much of the water break was at about 23 meters. The drilling was in October when the water table was at its lowest. ​This meant that after the following rainy season, ​we had so much water at our disposal.

Summary of Our Drilling Cost

​For the drilling only, we paid a total of USD2​700​ for the 80 meters excluding casing.

Summary of our expenses for drilling 80m

1. Initial 40m – USD1350.00
2. Additional 40m @ USD35/m – USD1400.00
3. 6m double PVC casing – USD180.00
4. Total: USD2930.00

​Due to the rock at our site, we only had to case the borehole for the first 6 m depth which was in double casing. 

More About ​Borehole Casing

Most boreholes drilled in Zimbabwe will require casing. The casing is PVC material, typically blue in color, as pictured that is inserted into the drilled hole to prevent borehole collapse. The casing which can be single or double gives the borehole needed collapse resistance. Double casing entails inserting a smaller diameter casing of 140mm into a larger diameter casing of 180mm.

​Although the main reason for borehole casing is for collapse resistance, casing is also important for guarding against water pollution, ​preventing water loss into nearby permeable strata, and facilitating continued drilling after the initial 6-meter depth among other purposes.

In areas such as Midlands in central Zimbabwe where there is ​much​ rock, casing is only required for the first 6 meters. Where there is such rock, boreholes rarely collapse. This is a good way to save on costs.

Borehole casings are rated according to class. In Zimbabwe, borehole drilling contractors mainly use two classes. Class 6 is the standard with Class 10 being the strongest​ and premium standard​. 

Most drilling companies usually supply these casings which are meant to last a very long time once installed. Due diligence must be performed to make sure the contractor does not use cheap classes on your borehole (see common tricks below). 

What Could Go Wrong When Drilling a Borehole in Zimbabwe

​In as much as the many boreholes drilled in Zimbabwe are completed successfully​, there are some things that can go wrong that you may need to be aware of:

1. Ending up with a dry hole – of all outcomes, this is perhaps the most dreaded. You can mitigate against spending money on a dry hole by using an experienced water siter with traceable references and a strong reputation for good outcomes. Furthermore, make sure the contractor drills exactly at the sited point. Do not shift the site even by a few centimeters.
2. Stuck drills – this can happen in areas where the rock is too hard. The drill rods or bit can get stuck in the rock permanently or so as to require retrieval back-up which may delay the project or render a promising hole unusable.
3. Borehole collapse – this can happen during, soon after, or sometime after the drilling works. Borehole collapse can render the hole unusable and is often caused by unstable or weak ground. As earlier stated, borehole casing is done to eliminate such collapses.
4. Borehole obstruction – this can happen if objects fall into the borehole during rig withdrawal. It can be so serious as to prevent the lowering of the pump at the lower stage, again rendering the hole useless. After drilling, the drilling constructor flushes the hole thoroughly to remove any debris. Make sure this is done well.
5. Rig breakdown – this can happen in two ways. Breakdown of the vehicle itself or the rig (machinery). This is why it is important to secure a drilling contractor of a good reputation with reliable equipment especially if your location is remote.
6. Inaccessibility – related to the foregoing point, problems with the accessibility of your site can suddenly become an issue on the day of the drilling. Our drilling contractor interviewed us about the road to our location, height clearance which can be compromised by tall trees, and so on. 

​When to drill a borehole in Zimbabwe

​If you wanted, you could drill a borehole any time of the year in Zimbabwe. For best results, it is prudent to attempt any drilling during the driest time of the year.

Drilling a borehole during the rainy season, for example, not only is ​it ​logistically difficult particularly in remote areas due to ​muddy roads​ and rain, but you also get a misleading water table.

Wet holes in peak dry times such as October almost guarantee all-year-round availability of water. During the rainy season, the borehole will yield even more water due to a higher water table.

It is for this reason that most boreholes in Zimbabwe are drilled between August and November just before the onset of the rainy season. As earlier mentioned, we drilled our borehole in October.

​Common Tricks Played in the Borehole Drilling Industry of Zimbabwe

​In the borehole drilling industry of Zimbabwe, we came to learn of a few tricks some dodgy contractors employ to your detriment.

1. Misrepresenting drilled depth – it costs money for the contractor to drill your borehole. Unethical contractors can cheat on this by misleading you about the actual depth drilled. An unscrupulous contractor can charge you for 80m drilled when the actual depth drilled is only 60m. How does this happen? It is important, first of all, to be present when your borehole is drilled. Second, most drilling rods are 4.6m long. At least 17 rods need to have gone underground to have drilled 80m. This simple tracking is important. Count the rods and agree each time. A good contract informs you each time they add a rod for transparency. Some contractors may become familiar with you, or chit-chat a lot at the site, so as to distract you from this important task. Keep your eye on the ball.
2. Misrepresenting casing and casing quality – in a similar fashion as rods, keep track of your casing count as the drilling is happening. Borehole casings in Zimbabwe have a standard length of 6m. A 60m deep borehole requires 10 lengths. Furthermore, casing quality varies with the cheaper version being of poor quality. Companies such as ProPlastics have a reputation for selling good quality products of this type. ​Furthermore, good quality casing has a digital stamp on them which you need to check when the materials arrive on site.​
3. ​Just one more meter boss – be careful that some borehole drilling contractors tend to ​want to play the one-more-meter card on you. This usually happens when you reach your targeted drilling depth and you still have a dry hole. They encourage you to drill one more meter in the hopes of finding a break. In desperation, it is tempting to go by the suggestion. Before you know it, that could be another 10 meters or USD350 (at USD35 per meter) and you still have a dry hole. Remember that this is your call, sometimes it is best to stop the drilling to save money, restrategize and try another site. The point is, be weary of being driven in a direction you never intended just because someone is persuasive or claims to be an expert.  

​What’s Next After the Drilling​

After successfully drilling the borehole, here are some necessary as well as obvious steps to follow:-

1. Seal the borehole opening –  the immediate thing to do is to seal the opening of the borehole to prevent any objects from falling into the hole. Depending on what falls into the hole, the borehole can be in danger of becoming unusable.
2. Test water capacity – to determine how much yield your borehole has, insert a submersible pump into the borehole and time how much water the borehole produces in an hour, for example. In our case, we timed how much it took to fill a 200-liter drum with underground water and extrapolated that to an hour. Also important to check is how long the pump runs before the borehole requires a recharge. 
3. Test water quality – depending on your location, there is a risk of your borehole producing contained water which may cause immediate or long-term illness if consumed by humans or animals. Although many people do not do these tests, they are nonetheless important, especially in urban areas or if you are located close to potential contamination sources.
4. Install a mechanism to draw water to storage – this is typically made up of a submersible pump, a power source that can be solar or mains. Also included is a storage tank which may or may not have a stand. You will also need a poly pipe that is of a length greater than the depth at which you are drilling. The poly pipe goes down the depth of your borehole together with the submersible pump for the purpose of bringing the water up to the surface. Once out on the surface, it must run to the storage tank.

The cost of these next steps will depend on a number of variables which include the size of your pump measured in horsepower, the number of solar panels, and the length of the poly pipe. Poly pipe is sold as a roll of 100 m and varies in size which is measured in millimeters (diameter) and class (6 or 10) as pertaining to the quality of the pipe.