Drilling a borehole can feel like a big achievement, especially when you’re getting closer to accessing a reliable source of water. However, knowing when to stop drilling is just as important as starting the process.
Drilling too deep can increase costs unnecessarily while stopping too early might leave you with an unreliable or insufficient water supply. So, how do you figure out the right point to stop?
At Borehole Drillers Nigeria, we often get asked, “When is the right time to stop drilling?” This article will walk you through everything you need to know, helping you make informed decisions that balance cost, safety, and water reliability.
Key Factors That Determine When to Stop Drilling
There are a few key factors to consider when deciding the right time to stop drilling your borehole. Each one plays a critical role in ensuring you’re drilling deep enough to access a stable water source without going overboard and inflating costs.
1. Water Yield and Flow Rate
One of the most important factors when deciding when to stop drilling is the water yield or flow rate. This is essentially how much water your borehole is producing per minute. Ideally, you want to stop drilling once you’ve hit a flow rate that is adequate to meet your needs. For example, if you’re drilling a borehole for domestic purposes, a flow rate of 20 to 30 liters per minute is typically enough.
However, if you need the borehole for irrigation, industrial, or commercial use, the required flow rate will be higher. In these cases, it’s important to continue drilling until you reach a yield that can support your intended usage.
A professional borehole drilling company will usually conduct a pumping test to measure the flow rate and ensure the yield is sufficient before deciding to stop drilling.
2. Striking a Reliable Aquifer
An aquifer is an underground layer of water-bearing rock or sand that provides a long-term, stable source of water. In borehole drilling, the goal is to reach a reliable aquifer that will supply water consistently over time. Once the drilling team hits a solid aquifer, this is often a good indicator that drilling can stop.
However, not all aquifers are created equal. In some areas, there may be shallow aquifers that don’t hold enough water to meet your needs over time. In such cases, it’s better to drill deeper to reach a more stable, deeper aquifer. A geological survey can help determine where these aquifers are located and whether the first one you hit will be sufficient.
3. Geological Conditions
The geological makeup of the ground plays a crucial role in determining how deep you need to go before stopping. Some areas in Nigeria, especially the Northern zones, have harder rock formations that require deeper drilling to access water. On the other hand, in some Southern regions, the water table may be higher, meaning you can stop drilling earlier.
A geological survey is usually conducted before drilling begins to understand the nature of the soil and rocks beneath your site. This survey can help you determine how deep you’ll need to go to access a reliable source of water. When drilling through rocky or complex terrain, stopping too early may mean you’ve missed reaching a deeper, more dependable aquifer.
4. Water Table and Seasonal Fluctuations
The water table is the level beneath the surface where the ground becomes saturated with water. While it’s possible to stop drilling when you hit the water table, this can be a mistake if you don’t account for seasonal fluctuations.
During the rainy season, the water table rises, and it’s easier to hit water at shallower depths. But during the dry season, the water table drops, and boreholes drilled to the shallow water table may dry up. It’s essential to continue drilling beyond the immediate water table to ensure that your borehole can access water even during drier months.
At Borehole Drillers Nigeria, we always recommend drilling deep enough to access water reliably year-round, which often means drilling past the seasonal water table.
5. Water Quality
Water quality is another critical factor in deciding when to stop drilling. Just because you’ve hit water doesn’t necessarily mean the borehole is complete. If the water quality is poor—such as water containing high levels of iron, manganese, or harmful bacteria—it may be necessary to drill deeper to access cleaner water.
For example, a friend of mine living in a North Central geo-political zone drilled a borehole, and after hitting water early on, they stopped. However, the water was heavily contaminated with iron, giving it a rusty color and metallic taste. Eventually, they had to drill deeper to find a cleaner, more usable water source.
Water testing can help determine whether the quality of the water you’ve hit is good enough to stop drilling or if it’s better to continue deeper.
6. Project Budget
Let’s face it—borehole drilling can be costly, and most people have a budget in mind. One of the challenges is balancing your budget with the need for a reliable water supply. The deeper you go, the more expensive the project becomes, as it requires more labor, materials, and equipment usage.
It’s important to work closely with your drilling company to establish a reasonable budget before you start. While it might be tempting to stop drilling early to save on costs, this could lead to problems in the future, especially if your borehole runs dry or the water quality is poor. A deeper borehole may cost more upfront, but it will often save you money in the long run by ensuring a more stable and reliable water supply.
Signs It’s Time to Stop Drilling
Here’s a summary of the key indicators that it’s time to stop drilling your borehole:
- Adequate water yield: If the pumping test shows the borehole is producing enough water to meet your needs, it’s a good sign that drilling can stop.
- Hitting a reliable aquifer: Once you reach a deep, stable aquifer, you can feel confident that you’ve hit a solid water source.
- Good water quality: If the water quality tests come back clear, there’s no need to keep drilling further.
- Achieving the right depth: When you’ve drilled beyond the seasonal water table and reached a depth that accounts for future water needs, it’s safe to stop.
Common Mistakes to Avoid
- Stopping too early: Don’t be tempted to stop as soon as you hit water. Make sure the water yield is sufficient, and the quality is good.
- Not accounting for seasonal changes: Always drill deep enough to ensure the borehole will provide water even during the dry season.
- Over-drilling unnecessarily: While deeper is often better, there’s no need to drill past the point where you’ve hit a reliable, clean, and sufficient water source.
Conclusion
Knowing when to stop drilling a borehole is crucial for ensuring you get a stable, long-term water supply without overspending on unnecessary depth. Factors like water yield, aquifer reliability, geological conditions, and water quality all play a role in determining the perfect stopping point.
At Borehole Drillers Nigeria, we have the expertise to guide you through the process, ensuring you stop at the right time—when your borehole is deep enough to provide a consistent water supply but not so deep that you’re paying extra for no reason. Contact us today to discuss your borehole project, and let us help you find the perfect depth for your needs.