Installation of a Submersible Pump in a Well or Borehole: Step-by-Step Guide

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Installation of a submersible pump in a well or borehole: step by step

The installation of a submersible pump may seem simple at first glance – you just drop it into the well, connect it, and you're done. In practice, it's not that simple. An incorrectly chosen submersion depth, a too short power cable, the absence of a check valve, or an improperly set pressure tank can destroy the pump within a few weeks, or the entire system may simply not behave as expected. Over the years of practice, we've seen dozens of installations where the problem was precisely in the details – the cable was twisted in a loop right next to the pump, the rope was too short, the gasket only sealed half. This article will guide you through the entire process from the first look into the well to the start of the water supply system in the household, including things that are often forgotten.

If you're still deciding which pump to choose for your well or borehole, we recommend reading the article Submersible pump for a well or borehole: which diameter and depth suits which pump – there you'll find a detailed overview of how to choose the right type according to the diameter of the borehole and the depth of the water level. We'll focus on the installation process here.

What you need to prepare before starting the installation

Good preparation will save hours of frustrating reinstallation of the pump from the well. These are the items you need to have prepared before the pump leaves the warehouse:

Submersible pump – for example, Submersible pump SKM 100 for wells and boreholes, suitable for wells and drilled wells with a diameter of 4 inches (100 mm) and up
Power cable – special cable for submersible pumps (so-called flat submersible cable H07RN8-F or equivalent), the length must correspond to the submersion depth + a minimum reserve of 2–3 m to the distribution board
Stainless steel cable or polyethylene rope – load-bearing element, min. diameter 4 mm for a pump up to 50 kg, always non-corrosive
Pressure hose or PE pipe – discharge pipe from the pump upwards, diameter according to the pump's discharge nozzle (most commonly 1" or 1¼")
Check valve – if not built-in directly in the pump, it must be mounted on the discharge nozzle
Pressure tank (hydrofor) – essential for a household water supply system, volume 19–100 liters depending on the need
Pressure switch – adjustable, most commonly Presscontrol or mechanical switch PM5
Cable clamps to the hose or pipe – plastic, every 1–1.5 m
Stainless steel connectors and clamps – no galvanized ones, they corrode and throw rust into the water
Sealant for threads – teflon tape and/or hemp for threaded connections
Steel or nylon carabiner – to secure the rope to the well head
Protective cover for the well or borehole head – seals the opening, prevents dirt, insects, and rainwater from entering
Multimeter and terminal block – for checking the electrical part

Recommended minimum list of tools: drill with accessories, torque wrench, insulation pliers, pipe wrench 32 and 40, shovel (if you need to dig around the well opening), work gloves, and helmet.

Well inspection before installation: what to find out and measure

Before you even unpack the pump from the box, you need to know several key values of your well or borehole. Installation without these data is done blindly.

Well depth and static/dynamic water level

The static water level is the depth at which the water stands at rest – without pumping. The dynamic water level is the depth to which the level drops during intensive pumping. The difference between them depends on the source's yield. For example, if you have a static level of 8 m and after an hour of intensive pumping it drops to 14 m, the dynamic level is 14 m. The pump must always be placed at least 1–2 m below the dynamic level, otherwise it will pump air and be damaged.

You can measure the total well depth by simply lowering a weight on a string to the bottom, marking it, and measuring. To distinguish between the bottom and the water level, you can use either visual (in clear water) or an electric probe (a light bulb connected in series, which lights up when in contact with water).

Diameter of the well or borehole

This is a critical parameter. Dug wells have a diameter of 80–120 cm and you can use almost any submersible pump. Drilled wells (boreholes) typically have a diameter of 110–160 mm (4–6 inches). The pump must have a body diameter smaller than the inner diameter of the borehole casing, with a minimum clearance of 5–10 mm on each side. The SKM 100 pump has an outer diameter of 98 mm and is therefore suitable for 4-inch (110 mm) boreholes.

Yield of the source

Yield indicates how much water the well is able to supply continuously (l/hour or l/minute). If you select a pump with a higher flow rate than the source's yield, you are pumping the well "dry" – this is the most common cause of pump damage. Roughly: a family house with 4 people needs a peak of around 30–40 l/min, but average consumption is much lower. You can find out the yield either from a hydrogeological assessment or empirically – you pump with a hand pump and measure the drop and recovery of the water level.

Step 1: Preparing the pump and accessories on the surface

Never install the pump directly from the box without checking. First, unpack it and check that it is not mechanically damaged. Test the dry run – only briefly, a few seconds – to confirm that the motor is running. A longer dry start will damage the pump.

Mounting the check valve

Install a check valve on the pump's discharge nozzle if it is not built-in directly inside (most modern submersible pumps have it, but always check the documentation). The check valve prevents reverse flow of water when the pump is off – without it, the pressure tank in the household would lose pressure and the pump would turn on several times an hour without any withdrawal, which would wear it out. Seal the threads with teflon, the flow direction on the valve must point upwards.

Connecting the discharge hose or PE pipe

For depths up to 30 m, a quality pressure hose (min. PN10) is sufficient. For greater depths and permanent installations, we recommend an HDPE pipe, which is stiffer, more durable, and easier to install together with the cable. Diameter: 1" for pumps up to 50 l/min, 1¼" for larger flows. Tighten the connection on the discharge nozzle with a torque wrench, but do not over-tighten – with plastic nozzles, cracking is a risk.

Securing the cable and rope to the hose

Secure the power cable and load-bearing rope to the discharge hose/pipe with plastic clamps every 1 m – 1.5 m. Reason: the cable must not hang freely, because when starting and lifting, it could twist, compress, or get stuck between the pump and the borehole wall. Route the cable parallel to the hose, not around it.

Secure the load-bearing rope directly to the mounting eye on the pump (not on the hose or cable). The rope is the primary load-bearing structure – when installing and lifting the pump, lift it by the rope, not by the hose.

Step 2: Lowering the pump into the well or borehole

This is the most physically demanding part, especially for greater depths. For boreholes over 30 m, we recommend working with at least two people.

Lowering procedure

Grasp the pump by the load-bearing rope and carefully start lowering it into the opening. Unwind the hose and cable at the same time without loops. Proceed slowly, checking that nothing gets stuck on the edges of the borehole casing. In dug wells, be careful of stone walls – avoid contact of the pump with the wall, otherwise vibrations cause abrasion of the cover.

Control the depth of lowering either with pre-prepared marks on the rope (e.g. with a marker every 5 m), or by measuring the hose. Stop the pump at least 1–2 m above the bottom of the well. Reason: in some wells, silt, sand, or mud settles at the bottom. A pump too close to the bottom would suck it in, which has a disastrous effect on the mechanical part (impeller, bearings).

Final position of the pump

To recap: the final position of the pump must be:

At least 1–2 m below the dynamic water level
At least 1–2 m above the bottom of the well (in wells with mud, ideally 2–3 m)
Within the entire range of the borehole casing, without contact with the wall

If these conditions do not match (e.g. the dynamic level is too close to the bottom), it is a sign that the source's yield is low and a pump with a high flow rate is not suitable for this well. The solution is a pump with a lower flow rate and built-in dry run protection (some models have a float switch or level sensor).

Step 3: Securing and sealing the wellhead

At the wellhead or borehole, you must securely fasten the rope, hose, and cable and seal the entire opening. This is very underestimated in practice, but it is extremely important for three reasons:

Water hygiene: An unsealed opening is an open path for rainwater, insects, rodents, and leaves directly into the source of drinking water.
Safety: The rope must be secured so that the pump cannot fall in the event of a disconnection.
Cable protection: The cable must not be bent over sharp edges at the borehole opening – at this point, mechanical damage to the insulation occurs.

For drilled wells, there are prefabricated borehole heads – steel or plastic flanges with rubber grommets for the hose, cable, and rope. We recommend using them always. For dug wells, stone or concrete covers with sealed lids are used.

Secure the rope to a load-bearing pin or carabiner built into the head or on the edge of the well. Make sure the rope carries the entire weight of the pump and the hose is not under tension.

Step 4: Connecting the discharge pipe and pressure tank

From the wellhead, you must route the discharge pipe to the technical room or to the location of the pressure system installation. For the external part of the routing, it applies: the pipe must be laid at a depth of at least 80–120 cm below the ground (below the frost line), or thermally insulated. If it passes through a foundation wall, protect it with a grommet and seal it.

Installation of the pressure system

A typical installation of a household water supply system with a submersible pump looks like this:

Discharge pipe from the well → input to the technical room
Closing valve (for service work without removing the pump)
Pressure tank (hydrofor) – minimum recommended volume for a family house: 50–80 liters, for garden use 19–24 liters is sufficient
Pressure switch – typically set to 2.0–2.5 bar (on pressure) / 3.5–4.0 bar (off pressure)
Pressure gauges – to monitor the tank's filling and system pressure
Filter – centrifugal or sand-grit, before the input to the household network
Distribution to the household

Before the first connection, check that the pressure tank is pre-set to the correct pre-pressure. The air pre-pressure must be 0.2–0.5 bar lower than the pump's on pressure. For example: on pressure 2.0 bar → pre-pressure in the tank 1.5–1.8 bar. This pre-pressure is set with a classic car pump via the air valve on the side of the tank (always with the water drained from the tank).

Step 5: Electrical connection of the submersible pump

The electrical installation of a submersible pump must meet the requirements of STN standards for wet operations and electrical appliances in the exterior. If you do not have electrical qualifications, leave this part to a professional.

Requirements for the electrical circuit

A separate circuit breaker for the pump circuit – at least 16 A (B characteristic) for common household pumps
Residual current device (RCD) with a tripping current of max. 30 mA
Earthing of the pump motor – mandatory, the cable must have a green-yellow protective conductor
Cable dimensioned for the starting current of the motor, not just the rated current – the starting current can be 5–7 times the rated current
Cable route from the distribution board to the well in a protective pipe (HDPE), buried or inside the building protected

Phase connection for three-phase pumps

Single-phase pumps (230 V) have a simple connection. Three-phase pumps (400 V) require the correct phase sequence – if the sequence is wrong, the motor rotates in the opposite direction and the pump does not pump (or pumps dramatically less). Always check the flow direction after the first connection. For the SKM series, single-phase power supply is standard, which simplifies the installation.

Step 6: First start-up, air venting, and setting

Before the first start-up, make sure all connections are sealed and the cable is not damaged. Open one tap or valve in the household – water needs somewhere to push out air during the first filling of the system.

First start-up procedure

Turn on the pump and observe whether water starts to flow. The first 30–60 seconds may have bubbles of air – this is normal.
Monitor the supply pipe – if water does not flow within 2–3 minutes, turn off the pump immediately and look for the cause (air pocket in the pipe, pump is too high, check valve is reversed).
When water flows, close the taps and let the pressure tank fill to maximum pressure (the pressure switch turns off). Read the value on the pressure gauge.
Check the pressure switch setting – if it turns off earlier or later than you want, adjust it according to the instructions (screws L and H on the switch).
Monitor the switching frequency – if the pump turns on more than 1–2 times per minute without withdrawal, the pressure tank has insufficient pre-pressure or is undersized.
Check the water quality – the first 10–20 minutes may have cloudy water (silt from the borehole during installation). Let it flow until it clears.

Setting the pressure switch in practice

The most commonly recommended settings for a family house:

On pressure (P-min): 1.8–2.2 bar
Off pressure (P-max): 3.5–4.0 bar
Difference P-max − P-min: at least 1.5 bar (otherwise too frequent switching)

For systems with a frequency converter (inverter controller), the setting is different and usually automatic – the pump maintains a constant pressure without a pressure tank or with a small 5-liter membrane tank. This solution is more suitable for large withdrawals and variable water demand.

Common mistakes when installing a submersible pump

Based on experience, these are the most common problems we encounter during service calls or complaints:

Pump lowered too deep (at the bottom): Suction of mud, rapid wear of the impeller. Solution: always at least 1–2 m above the bottom.
Pump lowered too shallow: Pumping air when the level drops, dry running, motor winding burnout.
Wrong cable cross-section: Voltage drop in a long cable causes the motor to receive lower voltage and overheat. Rule: for every 10 m of depth and every 1 kW of power, use one level thicker cross-section.
Missing check valve: Water flows back when the pump is off, the system loses pressure and the pump turns on unintentionally.
Missing load-bearing rope: The hose carries the weight of the pump, the connection loosens over time and the pump falls to the bottom. Extracting the pump without a rope from a 40-meter borehole is an extremely costly and complicated intervention.
Wrong pre-pressure in the pressure tank: The membrane is no longer used properly, the system turns on the pump too often (so-called water hammer).
Loose cable in the borehole: The cable is not tied to the hose and when lifting or lowering the pump, it twists and breaks.

If you are experiencing problems with an existing system, also see our article Common pump failures: why it doesn't pump, loses pressure or overheats – there you will find a detailed troubleshooting guide.

How long does the installation take and when to call a professional

An experienced craftsman can install a submersible pump in a borehole of up to 20 m depth, including connection, on his own in 3–5 hours. For depths over 30 m, three-phase connection, or more complex routing in the household, count on a full working day. Some tasks are better left to a professional:

Electrical connection – if you do not have electrical qualifications, it is a legal obligation to have it inspected
Extracting a stuck pump – at depths over 30 m without the right tools, you can worsen the situation
Installation of a frequency converter – setting it up requires experience with parameterization
Pumping test for yield – for new boreholes, this test is a condition for proper system dimensioning

For garden and temporary needs, where you do not want to deal with the entire water supply system, you can also consider motor-driven surface pumps. For example, Gasoline water pump BZP-20 is a self-priming motor pump suitable for clean water, which does not require any installation into a well and works anywhere with access to surface water up to a suction depth of about 7–8 m. For larger needs, where you need higher discharge or higher flow without connection to the electrical grid, also see Gasoline pump H-BZP-30 with a discharge of up to 95 m and a power of 9 690 W – this is a solution for really demanding situations such as farm water supply, construction sites, or emergency pumping. A comparison of pump types can be found in the article How to choose a water pump: gasoline, submersible or drainage?

Maintenance of the submersible pump after installation

A submersible pump is a "set and forget" device only to a certain extent. A few actions will significantly extend its lifespan:

Once a year: Check the pre-pressure in the pressure tank – air naturally escapes through the membrane. If the pre-pressure drops, pump it up.
Once a year: Check the setting of the pressure switch and the frequency of pump switching.
Every 3–5 years: Lift the pump from the well, visually check the condition of the cable, rope, and connections. Check with a probe whether the water level has changed.
Before winter (if the well is in an unheated building): Ensure that the pipe from the well to the house is below the frost line. If not, drain the pipe or add a cable heating tape.
Filter: Centrifugal or sand-grit filter before the input to the house should be cleaned according to the intensity of use, roughly every 3–6 months.

A more detailed guide to maintenance can be found in the article Maintenance and winterization of the pump: how to extend the life of gasoline and submersible pumps.

Examples from practice: three typical installation scenarios

Scenario 1: Dug well in the garden, depth 6 m, static level 3 m

A common situation in older family homes. Well diameter 100 cm. The pump is lowered to a depth of 5 m (1 m above the bottom, 2 m below the level). Discharge to the house is 15 m including elevation. A compact submersible pump with a flow rate of 30–40 l/min is sufficient. The system is supplemented with a 50-liter pressure tank and a mechanical pressure switch. The entire installation is manageable in one working day.

Scenario 2: Drilled well (borehole), depth 35 m, dynamic level 22 m

Borehole diameter 5" (127 mm). The SKM 100 pump is lowered to 24 m (2 m below the dynamic level). The cable must have a minimum diameter of 3×1.5 mm² for a single-phase motor up to 1 kW. Steel cable 4 mm. Discharge to the house via 60 m of buried pipe + 10 m elevation = total discharge ~70 m. The system is dimensioned with an 80-liter pressure tank. The electrical part is handed over to an electrician for installation and inspection.

Scenario 3: Garden irrigation without a permanent installation

The customer wanted to irrigate the garden from an old well, but did not want to invest in a full water supply system. Solution: submersible pump lowered on a rope and PE hose directly into the well, without a pressure tank, controlled by a manual switch. No pressure switch. The pump is turned on manually before irrigation and turned off after completion. Costs are significantly lower, functionality is fully sufficient for seasonal use.

Frequently asked questions (FAQ)

Do I need a permit or inspection for the installation of a submersible pump?

The electrical connection of the pump (especially a new circuit in the distribution board) must be carried out by a person with the appropriate electrical qualification and must be inspected. Lowering the pump into an existing well does not require a building permit, provided it is an existing well. A new drilled well, however, requires a hydrogeological survey and in many cases also a notification or permit from the water management authority.

How long does a submersible pump last without service?

A quality submersible pump with proper installation, proper position (not too deep, not dry), and with functional protection can last 8–15 years. The most common cause of premature failure is dry running (water level dropping below the pump), overload caused by a blocked impeller, or mechanical cable damage. A regular annual check of the water level and pressure tank significantly reduces these risks.

Can I leave the submersible pump in the well over winter?

If the pump is under water, it is also below the frost line and will survive the winter. The problem is not the pump itself, but the supply pipe from the well to the house – if it runs only shallow or on the surface, it will freeze. Ensure that the entire pipe route is buried at least 80–100 cm below the ground, or use electric heating tape on critical sections. Details in the article Maintenance and winterization of the pump.

Can I use a regular garden hose instead of an HDPE pipe for the discharge pipe?

For temporary use and smaller depths (up to 10 m) yes, but not for long-term use. Regular garden hoses are not dimensioned for a constant pressure of 3–4 bar and constant submersion. They degrade, harden, crack, and release impurities into the water. For a permanent installation, always use certified HDPE pipe PN10 or a pressure hose with a maximum working pressure marking.

The pump turns on every minute even without water withdrawal – what's wrong?

This is a classic sign of an undersized pressure tank or incorrect pre-pressure. Check the air pressure in the tank (with water drained from the tank) – it must be 0.2–0.5 bar below the switch's on pressure. If the pre-pressure is correct, the tank may have a damaged membrane – water and air are not separated and water takes up the entire volume of the tank. In this case, the tank must be replaced. Faults of this type are also described in the article Common pump failures: why it doesn't pump, loses pressure or overheats.

How far away from the house can I have a well with a submersible pump?

The distance is limited by pressure losses in the pipe and voltage drops in the cable. From a hydraulic point of view: the longer the route and the smaller the pipe diameter, the greater the pressure drop (about 0.1–0.2 bar per 10 m of horizontal pipe at a normal diameter of 1"). From an electrical point of view: use a thicker cross-section for a long cable. For distances up to 50 m from the house, there is no problem, for 100 m and more, a calculation is needed. More about calculations can be found in the article Discharge and power of the pump: how to calculate what you need for the garden or well.

Conclusion: Installation that serves for years without problems

A submersible pump is a robust and reliable device if installed correctly. The key points that determine the longevity and reliability of the system are: correct submersion depth (below the dynamic level, above the bottom), dimensioned cable, load-bearing rope, functional check valve, correctly set pressure tank, and protection against dry running. These details do not cost extra money, they just require attention during installation.

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