Installation of Submersible Pump in a Well or Narrow Borehole
Installation of a submersible pump in a well or narrow borehole
Installation of a submersible pump is one of the tasks where it pays off to invest more time in preparation than in the actual lowering of the pump into the water. While with surface pumps it is usually sufficient to connect the suction and discharge piping and the electrical wiring, in the case of submersible pumps in a well or narrow borehole, dozens of small details determine the pump's lifespan and trouble-free operation — from the method of securing the rope, through the choice of pump diameter, to how precisely you route the cable along the discharge pipe. In this article, we will go through the entire installation process step by step, explain typical mistakes we see during service interventions, and also show technical details in the form of diagrams.
If you are still choosing the right type of pump, we recommend first reading the articles "How to choose a submersible pump for a well or borehole" and "What borehole diameter do you need: the difference between 2", 3", and 4" pumps." This article focuses exclusively on the installation itself — that is, the physical installation of the pump you have already selected or purchased.
Preparation before installation — what to check first
Most of the problems we deal with in service already arise during preparation, not during the actual lowering of the pump into the borehole. Therefore, we recommend going through the following checklist before you even unpack the pump from the box.
Measuring the actual diameter and depth of the borehole
The diameter of the borehole or well casing is a completely essential parameter. Drilled wells are commonly lined with pipes with an internal diameter of 2" (approximately 50–51 mm), 3" (approximately 75–76 mm), or 4" (approximately 100–102 mm), but in practice, we also encounter atypical diameters, especially in older wells or in boreholes drilled by hand. Before purchasing and before installation, always physically measure the internal diameter of the casing using a caliper or at least estimate it based on the external diameter of the pipe and wall thickness.
Equally important is knowing the actual depth of the borehole and especially the depth of the water level — static (at rest) and dynamic (during pumping). These data directly influence the depth at which you hang the pump, the length of cable and rope you need, and the lift the pump must handle. A more detailed discussion of choosing performance based on depth is covered in the article "What pump power and lift to choose based on well depth."
Checking the quality and cleanliness of the water
For both new and older wells, it pays off to check before permanent installation whether the water contains an excessive amount of sand or fine sediments. If the borehole "sands," meaning it carries fine particles during pumping, it is advisable to use an Anti-sand filter 1" for suction, which is mounted on the pump's suction inlet or directly on the pipe just before the pump. This prevents the impellers from clogging with sand, which is one of the most common causes of premature wear of submersible pumps.
Choosing the correct type of pump according to the borehole diameter
The pump diameter must have sufficient clearance in relation to the internal diameter of the casing — a minimum reserve of 4–6 mm is recommended to ensure the pump does not rub against the pipe wall during lowering, especially if the borehole is not perfectly straight or has slight deformations in some places.
- Narrow 2" boreholes — suitable are shaft (screw-type) pumps with a small diameter, for example, Submersible shaft pump for narrow borehole STING 2". These pumps have a slim design and are specifically constructed for installation in narrow casings.
- 3" and wider boreholes — here there is room for more powerful centrifugal pumps with higher flow rates, for example, Submersible pump IBO 3" STM 20, which can supply larger households or irrigation systems.
Differences between shaft and centrifugal principles, including when each type is suitable, are discussed in detail in the article "Submersible shaft pump vs. centrifugal — differences and applications," and a direct comparison of specific models can be found in the article "Comparison of STING and IBO pumps — what to choose."
Diagram — difference between 2" and 3" borehole
Required components and materials before installation
Before lowering the pump into the borehole, you should have all components ready, because buying additional items during installation (especially when the pump is already partially lowered) is impractical and sometimes risky.
List of required materials
- Stainless steel or galvanized rope (or high-quality polypropylene rope with sufficient load capacity) for securing the pump
- Discharge piping — PE pipe in coils, PPR, or galvanized pipes depending on depth and type of installation
- Submersible cable with sufficient conductor cross-section in relation to the length and power of the pump
- Water-resistant tie wraps (UV stable, best stainless steel clamps or plastic cable ties)
- Connector/bracket for securing the rope and cable to the wellhead (well head or at least a through bracket)
- Check valve (if not part of the pump)
- Sand filter, if the water is sandy
- Pressure gauge, or pressure tank and automation, if connected to the house distribution system
Important note on the rope: the pump must never be suspended only by the discharge hose or cable — these components are not designed to bear the full weight of the pump and the column of water in the pipe. Always use a separate securing rope that takes the full load.
Step-by-step installation procedure
The following procedure is based on common practice when installing submersible pumps in boreholes with diameters from 2" to 4" and is applicable to most domestic and small commercial wells.
1. Assembling the components on the surface
The pump, rope, cable, and discharge piping are assembled into one unit on the surface, at the mouth of the borehole. The rope is attached to the top eye or hook of the pump, and the discharge piping is screwed or slipped onto the discharge outlet (depending on the type of thread or system — with PE piping, clamping or screw-on couplings with anti-loosening protection are often used due to pump vibrations).
2. Routing and securing the cable
The power cable is routed parallel to the discharge piping and is fixed to the piping with tie wraps at regular intervals — it is recommended to secure it every 1.5 to 2 meters. The cable should never hang freely next to the piping, as during lowering and during operation (pump vibrations, water flow) it can rub against the borehole wall, which is one of the most common causes of short circuits and pump failure after a few months of operation.
3. Gradual lowering into the borehole
The pump is lowered slowly and smoothly, never allowed to drop freely. During lowering, it is important to monitor whether the assembly encounters excessive resistance — if the pump suddenly gets stuck, it likely indicates an obstacle in the borehole (narrowing, sediment, casing damage), and you should stop and resolve the issue, not continue forcefully.
4. Positioning above the bottom of the borehole
The pump is never installed at the very bottom of the borehole. A safe distance is at least 1–1.5 meters above the bottom to prevent the pump from sucking up settled silt and sand, which naturally accumulates at the bottom. At the same time, the pump must be sufficiently submerged below the dynamic water level (i.e., the level during pumping, not at rest) — a reserve of at least 1–2 meters below the lowest expected dynamic level is recommended to prevent air intake and dry running when the water level drops during prolonged pumping.
5. Fixation on the wellhead
After reaching the desired depth, the rope, cable, and pipe are fixed to the wellhead using a wellhead or console. This head also serves as a seal to prevent the entry of dirt, insects, and surface water, which is important from a hygiene perspective as well.
Schematic - pump lowering procedure into the well
Electrical connection and pump protection
Submersible pumps are typically single-phase (230 V) or three-phase (400 V), depending on the power and model. In the case of single-phase pumps, it is common for the control electronics (capacitor, dry-run protection) to be built directly into the pump head or in a separate external box, which is placed outside the well, in a dry and protected location.
Basic principles of safe electrical connection:
- The pump must be connected via a separate circuit breaker with an appropriate rated value according to the power consumption
- Installation of a residual current device (RCD) with a sensitivity of 30 mA is recommended
- The connection between the submersible cable and the supply cable (if the pump cable is not long enough) must be made using a waterproof compression coupling or sealing kit - ordinary insulation tape is not sufficient here
- Dry-run protection (float switch, pressure sensor, or electronic protection) should always be installed, as running the pump without water reliably damages the motor and impeller within minutes
Schematic - simple connection of a submersible pump with dry-run protection
Mounting specifics into a narrow 2" well
Mounting into narrow 2" wells has several specific features compared to wider 3" and 4" wells, which is good to know in advance, as there is minimal space for manipulation and errors are harder to correct.
Smaller tolerance for well irregularities
In narrow wells, even a minor deformation of the casing, a protruding welded joint of the pipes, or sediment can cause the pump to get stuck during lowering. Therefore, it is recommended to lower only a plumb bob on a rope into the well before the first installation to verify the passability along the entire length.
Shaft pumps as a solution for narrow diameters
These narrow spaces are specifically designed for shaft (threaded) pumps such as STING 2", which have a more compact construction than centrifugal pumps with comparable performance. The shaft principle also better handles slightly contaminated water with sand content, which is a common occurrence in narrow, often older drilled wells.
Less space for cable and pipe
There is minimal space between the pump and the casing wall in a narrow well, so the cable should be routed as closely as possible to the pipe and thinner, yet still adequately dimensioned, cable ties should be used to ensure the total assembly thickness does not exceed the internal diameter of the well.
Mounting specifics into wider 3" and 4" wells
In wider wells, the technician has significantly more space for manipulation, which allows the use of more powerful centrifugal pumps, for example IBO 3" STM 20. These pumps generally have a higher flow rate and are suitable for supplying larger households, garden irrigation, or operations with higher water consumption.
However, even here, a wider space does not mean less need for precision - the cable must still be properly secured, the rope must be dimensioned for the actual weight of the assembly (pump + water-filled pipe), and the check valve must be functional to prevent backflow and water hammer after the pump is turned off.
Common installation errors from practice
Over the years of service interventions, the same errors repeat themselves, leading to premature failures or the need to re-lift the entire assembly from the well - which is an unpleasant and time-consuming task at depths of 30-60 meters.
- Suspending the pump only on the cable or hose - without a separate rope, the cable or connection will eventually break, and the pump will fall to the bottom of the well.
- Too shallow pump placement - during dry months when the water level drops, the pump draws in air, runs dry, and damages the motor or mechanical seal.
- Lack of dry-run protection - the most common cause of complete pump destruction, which can be easily avoided with a float switch or electronic protection.
- Improperly dimensioned cable - at greater depths and longer supply cables, voltage drop must be considered; a thin cable causes overheating and insufficient motor performance.
- Ignoring sandy water - without a sand filter, sand gradually wears out the impeller and seals, which can reduce the pump's lifespan by up to half.
- Cable hanging loosely next to the pipe - without securing, the cable rubs against the well wall, which over time causes insulation damage and short circuits.
- Mounting the pump directly on the bottom of the well - suction of silt and sand leads to rapid wear and reduced efficiency.
A more detailed overview of typical faults and their solutions can be found in the article "Most common submersible pump failures and how to solve them."
How the installation of a submersible pump differs from a surface pump
If you are considering whether a submersible or surface pump is more suitable for your well, you should consider that the installation of a submersible pump is physically and time-consuming - it requires lowering into the well, working with a long rope and cable, and in the case of a failure, pulling the entire assembly back up. In contrast, a surface pump is installed outside the well, which makes maintenance easier, but it has a limited suction lift (physically up to around 8-9 meters, practically less) and is therefore suitable only for shallow wells. A detailed comparison of both types can be found in the article "Submersible vs. surface pump for water from a well: which is more cost-effective."
Commissioning and first start-up
After the installation is completed, the first start-up follows, which should be carried out carefully and under supervision.
- Check the correct direction of motor rotation (for three-phase pumps - incorrect rotation is clearly indicated by reduced performance and a noisier operation)
- During the first start-up, let the pump run briefly, monitor pressure and flow, and bleed the pipe as instructed by the manufacturer
- Check for water leakage at pipe connections and at the pump head
- Verify the functionality of the dry-run protection - for example, by briefly simulating a drop in water level, if the design allows it
- Note the submersion depth of the pump, cable length and type of components used - these details will be useful for future service
Maintenance after installation
Even a properly installed pump requires regular inspection. It is recommended to check the functionality of the dry-run protection, the condition of electrical connections on the surface (in the control box, in the well head), and in the case of sandy water, also the condition of the sand filter, which should be cleaned or the insert replaced regularly. If the pump performance drops or unusual noise occurs during operation, it is advisable to inspect the pump as soon as possible, as early intervention often saves the motor, while a delayed action may result in a complete pump replacement.
Cable and rope fastening on the pump head - correct load distribution
The way the rope is attached to the upper eye of the pump determines how the load is distributed between the rope, cable and pipe during the entire operation. The rope must be led freely directly from the load-bearing eye of the pump, while the cable and pipe are only fixed to it using tie wraps - never the other way around. If this hierarchy is reversed and the cable or pipe connection takes the load, it gradually loosens and in the case of longer wells, eventually leads to the pump falling.
Frequently asked questions (FAQ)
How deep should I submerge the pump below the water level?
It is recommended to submerge it at least 1-2 meters below the lowest expected dynamic water level (i.e., the level during pumping, not at rest), and at the same time at least 1-1.5 meters above the bottom of the well, so that the pump does not suck up settled silt and sand.
Can I suspend the pump only on the discharge hose without a rope?
No. The discharge pipe or cable is not designed to carry the weight of the pump and the water column. Always use a separate securing rope attached to the upper eye of the pump.
What pump diameter should I choose for a 2" well?
For 2" wells, slender shaft pumps such as STING 2" are suitable, as they have sufficient clearance in relation to the internal diameter of the casing and also handle slightly contaminated water better. More detailed criteria can be found in the article What pump diameter do you need - 2" or 3" well.
What to do if the water from the well contains sand?
We recommend installing Sand filter 1" for suction directly on the pump's suction inlet or on the pipe just before the pump. This prevents clogging of the impeller and premature wear of the pump.
Is dry-run protection necessary?
Yes, definitely. Running the pump without water leads to rapid motor overheating and damage to the mechanical seal, often within a few minutes. This protection is one of the most important elements of the entire installation.
How often should the pump be serviced or inspected?
It is recommended to inspect electrical connections, the functionality of protective elements, and in the case of sandy water, also the condition of the filter at least once a year. Any changes in performance or pump noise should be addressed as soon as possible.
Conclusion
Installing a submersible pump into a well or narrow borehole is not a complicated task if basic technical guidelines are followed - correctly measured well diameter, quality securing rope, proper cable fixation, sufficient submersion depth below the dynamic water level, and functional dry-run protection. Most of the problems we encounter in practice do not result from the pump itself, but from an incomplete installation or underestimating the preparation. If you are unsure about the correct pump selection for your specific well, we recommend also reading the articles How to choose a pump for a well: key selection criteria and Comparison of STING and IBO pumps - what to choose, where you will find specific recommendations according to the well diameter, depth and required performance.
Do you have a question about this topic?
Are you unsure or dealing with a specific situation in your household? Write to us - we are happy to help.