Drilled Well Shaft: What It Must Meet and How to Connect It to the Water Supply

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Well shaft for a drilled well: what it must meet and how to integrate it into the water supply system

A drilled well is the most reliable source of drinking water for many homeowners – independent of the public water supply, available all year round, and financially advantageous with proper design. However, the well itself is only the beginning of the story. Between the borehole and the kitchen tap lies a whole system of components, one of the most important – and often underestimated – being the shaft. This technical "room" underground not only protects the valves and electrical installation from frost, but also serves as a service node through which the entire water supply system regulates pressure and can be repaired without having to dig up the garden.

In practice, we come across cases where the investor paid tens of thousands of euros for a quality borehole, bought a top-brand submersible pump and a water tank – and the shaft was "handled" with a cheap concrete block from the neighbor's son. Three winters later, they call to say that their pipe has frozen, there are mice in the shaft, and they don't know where the shut-off valve is. This article is about how to avoid such scenarios.

Why a drilled well needs a shaft and what exactly is inside it

Laypeople sometimes think that a shaft is just a "hole in the ground where the pipe is". In reality, it is a technical facility that performs several irreplaceable functions at once:

Protection against frost: All valves, shut-off valves, pipe penetrations, and connections must be placed below the frost line, which in Slovakia ranges from 80 cm in the southwest to 120–140 cm in more mountainous areas. The shaft creates an insulated space where the temperature does not drop below zero even in extreme winters.
Service accessibility: Submersible pumps need to be removed every few years, shut-off valves need to be turned, and valves need to be checked. The shaft allows these tasks to be performed without digging up the terrain.
Protection against contamination: The borehole is the "entrance" to the water source. If it is not placed in a watertight shaft, surface water, manure, or pesticides can enter the well directly with every rain.
Protection of the electrical installation: The cable of the submersible pump, the control cable, and possibly sensors – all of this runs through the shaft. Proper placement and moisture drainage are essential for the safety and longevity of the electrical system.
Place for measurement and regulation: A water meter (if required by the authority), pressure gauges, shut-off valves, and pre-filtering units – all of this logically belongs in the shaft and not in the technical room in the house, where it would complicate installation and service.

What type of shaft is suitable for a drilled well

On the market, there are concrete, masonry, and plastic (PP – polypropylene) shafts. For drilled wells, plastic prefabricated shafts are now clearly dominant, for several reasons:

Water tightness: Concrete rings are only difficult to make watertight at the joints. With fluctuations in the groundwater level, infiltration occurs, the shaft fills with water, and the valves corrode. Monolithic plastic shafts are watertight from the factory – the walls are made of solid plastic, without joints in critical areas.

Weight and installation: A plastic shaft weighs a fraction of a concrete one. One worker can carry it, place it in the excavation, and the entire installation is simpler. This reduces installation costs and excavation time.

Self-supporting: High-quality plastic shafts (for example, Round PP water meter shaft 1300x1000 plastic self-supporting or Round PP water meter shaft 1600x1000 plastic self-supporting) are designed as self-supporting structures that can withstand lateral soil pressure and loading from traffic (when placed under a driveway).

Lifespan: PP shafts have a declared lifespan of 50 years or more, are resistant to weak acids and alkalis, do not rust, and are not subject to biological degradation.

A more detailed comparison can be found in the article Plastic shaft vs. concrete shaft: what is more cost-effective? in our Knowledge Center.

Shaft dimensions: how to choose them correctly

The size of the shaft depends mainly on what will be inside it and what level of service comfort you want to ensure. The basic parameter is the internal diameter (or clear width for rectangular shafts) and depth.

From practice it follows:

Diameter 600–800 mm: Absolute minimum, suitable only for a simple borehole passage without fittings. Installation and maintenance are almost impossible in this space.
Diameter 1000 mm: Acceptable solution for simple applications – borehole, shut-off valve, check valve. Maintenance is possible, but it is tight.
Diameter 1300 mm: Recommended standard for a family house. Sufficient space for a water meter, shut-off valves, filtration group and comfortable work. Shaft PP 1300x1000 is a solution we recommend in 90 % of family house cases.
Diameter 1600 mm: Suitable if you plan a more extensive fitting group, pressure vessel directly in the shaft (some investors prefer this), or a combination of a borehole and inspection elements. The corresponding solution can be found as Circular water meter shaft PP 1600x1000 plastic self-supporting.

The depth of the shaft depends on the depth of pipe laying, i.e. on the frost depth in the given location. A standard shaft height of 1000 mm is usually sufficient for a depth of the bottom of 1.0–1.2 m below ground level. If the borehole discharges deeper, the shaft can be extended with an extension ring or ordered to measure. The issue of depth is discussed in more detail in the article Depth of shaft installation: how to properly place the shaft below the frost level.

Legislative and technical requirements for the shaft at a drilled well

The construction of a well in Slovakia is subject to the water law (Act No. 364/2004 Coll. on water) and the building law. A well as a water construction requires either a notification or a building permit depending on the parameters of the borehole. The shaft is part of this water construction and therefore must meet certain technical requirements:

Water tightness: The shaft must not be a source of contamination of groundwater and must not allow surface water to enter the borehole. Pipe and cable passages must be sealed.
Hygienic protection zone: The borehole must have a hygienic protection zone of the first degree with a radius of usually 10 m (for individual wells it may be reduced). The shaft must be part of this zone.
Shaft cover: It must be lockable or at least secured against unauthorised access and against the entry of animals.
Ventilation: The shaft must have ventilation – either through a cover with a ventilation grid or through separate ventilation openings. Without ventilation, condensation accumulates and damages the electrical installation.
Drainage from the shaft: Water that accumulates in the shaft (condensation, minor leaks) must have a possibility of drainage. The shaft must not be a "swimming pool".

During the commissioning of a water supply from a drilled well (if it is for a residential house or several consumers), the environmental administration may require a record of the shaft construction, its dimensions and type of material.

What must be in the shaft: a comprehensive fitting group

The shaft is not just a "cover for the borehole". It is a functional node of the entire waterworks. Let's look at what belongs in it and why:

1. Borehole passage through the bottom of the shaft

The borehole (steel or plastic casing) passes through the bottom of the shaft. This connection must be watertight – standard use is an EPDM rubber gasket or hydro-insulating seal. If the passage is not tight, surface water will seep into the borehole and contaminate the entire source.

2. Shut-off valve (ball valve)

Directly after the borehole passage, as low as possible in the shaft, there must be a shut-off valve that allows the water to be turned off without switching off the pump (e.g. when replacing fittings higher in the system). We recommend a brass or stainless steel ball valve DN 32 or DN 40 according to the pipe diameter.

3. Check valve

The check valve prevents reverse flow of water from the pressure pipe back into the borehole in the event of a pump failure. Without it, the pressure tank would empty and the pump would run "dry" for a fraction of a second each time it starts, until the water column is restored. In the long term, this destroys the pump. Some submersible pumps have a check valve built into the pump body – in this case, the shaft check valve is a backup safety measure, but still recommended. The topic of check valves is discussed in the article Protection against reverse flow: when do I need a check valve in the shaft?

4. Water meter

If the well is operated under a permit or if the water is billed (e.g. supply to several households), a water meter is mandatory. Even for your own consumption, a water meter is a good tool – monitoring consumption will detect leaks or abnormal pumping long before you notice it on your electricity bill.

5. Pressure group and filtration

It is logical to place a pre-stage filtration (sediment filter 50–100 μm) in the shaft, which captures sand and silt from the borehole before it reaches the pressure system and the household distribution. The filter must be removable and cleanable from the shaft – this is another reason why a sufficient internal diameter of the shaft is so important.

6. Electrical installation

The supply cable of the submersible pump and the control cable (if the pump is controlled by a frequency converter or pressure switch) must be routed in a protective conduit in the shaft. The electrical box (terminal box) must have at least IP 54 protection. The cable must not be freely placed on the bottom of the shaft – moisture and possible water would damage it.

How to connect the shaft to the waterworks: step-by-step procedure

The entire system from the borehole to the tap in the house forms one unit. Let's look at the logical sequence of connection, since errors in this phase are often hidden for years and their consequences only appear in the event of a failure or during maintenance attempts.

Step 1: Installing the manhole into the excavation

The excavation must be 15–20 cm wider than the outer diameter of the manhole to allow for working space around it. The bottom of the excavation is leveled with a layer of gravel (10–15 cm), and the manhole is installed so that the cover is approximately 5 cm above ground level (protection against surface water). The borehole casing must pass through the bottom of the manhole tightly – the passage is sealed with a gasket.

Step 2: Installing fittings in the manhole

The procedure is from bottom to top: passage gasket → check valve → ball valve → water meter → filter. Each connection must be accessible from the manhole cover. We recommend using dielectric unions where copper and zinc meet (to prevent galvanic corrosion).

Step 3: Routing the pipe from the manhole to the house

The pipe (PE-HD, diameter according to calculation – typically DN 32 for a detached house) is laid at a depth of at least 1.0–1.2 m (below the frost line) to the house's entrance wall. Another shut-off valve must be installed at the house entrance. The pipe must not have any air pockets (rising sections without venting) – otherwise, the pump loses efficiency and water hammer may occur upon repeated startup.

Step 4: Electrical connection

The pump cable runs from the borehole through the manhole (in a protective conduit) to the technical room, where the pump control panel (pressure switch, fuses, possibly a frequency converter) is located. In the manhole, the cable is connected in a certified waterproof junction box – never "on a black wire wrapped in tape".

Step 5: Pressure tank and water supply system

The pressure tank (hydro-pneumatic unit) is installed in the technical room of the house, not in the manhole – it is too large, and the membrane's pre-pressure cannot be easily adjusted in the manhole. Only the pressure gauge and possibly a pressure sensor remain in the manhole. After the pressure tank come additional filters (carbon, softener), if needed according to the water analysis.

Manhole and drainage: when to use a pumping manhole and what to do with waste

Manholes near wells solve the water supply. In practice, however, solutions are often also needed on the waste water side – and this is where integration with the sewer infrastructure comes into play. If the terrain is lower than the sewer line, or if the house is located in an area without public sewerage, it is necessary to handle the waste with a pumping manhole.

For these situations, the Pumping sewer manhole MIDI 1600x1000 or its smaller version Pumping sewer manhole MIDI 1300x1000 are suitable. These manholes are complete units that include a plastic tank, a submersible pump for sewage, a float switch, and a discharge pipe.

Also related is the protection against backflow: if the house is located in a flood-prone area or the sewer connection is at a lower level, the system should also include a manhole base with check valve 400/160, which physically prevents backflow of sewage into the house in case of rising levels in the sewer.

At family homes with a drilled well, we can therefore have two types of manholes in the same garden: a water supply one (for water from the borehole) and a pumping sewer one – and both must be properly designed to function as a system. Details on the correct selection were covered in the article How to choose a manhole: water meter, inspection or pumping?

Most common mistakes in the installation of a manhole for a drilled well

Over the years of practical experience, the same problems keep repeating. Here are the most common ones we see:

Manhole installed too shallow: The cover is conveniently accessible, but the bottom of the manhole is only 60 cm below ground level. In a harsh winter, the fittings will freeze, the water meter will crack, and the filter fuse will become unusable.
Manhole without ventilation: Condensation in a sealed plastic space with changing temperatures causes rapid corrosion of electrical connections and mold growth on thermal insulation.
Leaky borehole passage: After the first heavy rain, the manhole fills with water, the electrical installation is under water, and the water meter is in murky water.
Missing shut-off valve: Without a shut-off valve directly in the manhole, it is not possible to repair the pipe in the house without completely stopping the pump and waiting for the pressure tank to empty. In case of an urgent breakdown, this can mean hours of downtime.
Manhole too small for the planned equipment: The investor orders the cheapest DN 600 manhole, then wants to add a filter and a water meter – but it simply does not fit. Result: the filter is outside and not connected, or the manhole is removed and replaced with a larger one.
Cable without a protective conduit: The submersible pump cable lies freely at the bottom of the manhole in standing water. After years, moisture penetrates the insulation, causing a short circuit and a burnt-out pump.
Incorrect slope of the cover: The cover is below the level of the surrounding terrain and functions like a "rainwater tray". After every rain, the manhole fills up.

Maintenance of a well shaft: what and when to check

A well shaft does not require intensive maintenance, but regular checks prevent costly repairs. Recommended schedule:

Every year (spring): Open the manhole cover and visually inspect the condition of the fittings for signs of corrosion, water leakage or condensation. Check the condition of the sealing of the pass-through and electrical connections.
Every 2 years: Clean the sediment filter (replace the insert). Check the water meter reading and compare it with the electricity consumption of the pump – unexpected deviations indicate leaks or a change in pump performance.
Every 5 years: Complete electrical inspection in the shaft (cable, terminal block, coverings). Operate the shut-off valves and check valve to prevent them from "seizing". Check the condition of the inner surface of the shaft (cracks, deformations in self-supporting PP shafts are signs of improper backfilling).
If you have doubts about water quality: Have the water tested. A drilled well is not guaranteed to be trouble-free – groundwater quality can change due to activities in the surrounding area (agriculture, construction, industry).

Common problems, along with their causes and solutions, are discussed in detail in the article Common faults of shafts and pumping units: causes and solutions.

Estimated costs and economic evaluation

An investment in a quality plastic shaft ranges roughly from 250 to 600 EUR for the shaft alone, depending on diameter and height. Add fittings (shut-off valve, check valve, water meter, filter) at 200–400 EUR, electrical work in the shaft at 100–200 EUR, and earthworks (excavation, backfilling) at 300–600 EUR depending on depth and access for machinery. Overall, a shaft for a family house ranges from 800 to 1,800 EUR including installation.

This is a one-time investment that extends the life of the entire water supply system by decades. A submersible pump without protection lasts on average 5–8 years. A well-designed system with a shaft, check valve and frequency converter lasts 15–20 years without major faults. Calculate for yourself what pays off.

Frequently asked questions (FAQ)

Do I need a shaft for every drilled well, or is a manhole cover directly on the borehole sufficient?

Technically, it is possible to install the shut-off valve and pass-through directly on the borehole head without a shaft, but in practice, it is not suitable. The fittings are exposed to frost, handling is limited, and there is no space to install a filter or water meter. In addition, hygiene regulations require protection of the borehole from contamination, which the head alone without a shaft cannot ensure. A shaft is standard, not a luxury.

What depth of the borehole is needed so that the pump does not start "dry" in winter – does it depend on the shaft?

The depth of the borehole depends on hydrogeological conditions, not the shaft. However, the shaft does influence where the check valve is located and how long a water column the pump must lift at start-up. A properly placed check valve (as close as possible to the borehole outlet, i.e., in the shaft) minimizes the volume of water that drains back after a pump failure – and the pump restarts sooner while still under water.

Can I place a pressure tank (hydro-pneumatic tank) directly in the shaft to save space in the technical room?

Theoretically yes, if the shaft is large enough (at least 1,600 mm in diameter) and the tank is properly secured against movement. In practice, it complicates maintenance – when inflating the pre-pressure of the diaphragm, you need access to the valve, pressure measurement and handling of tools in the limited space of the shaft. Most technicians do not recommend it. An exception are compact diaphragm tanks of small volume (up to 24 l), which can be placed in the shaft as auxiliary pressure equalizers.

What if the shaft fills with water – do I need to pump it out, or is it normal?

Water in the shaft is not normal and indicates a problem. The causes are threefold: a leaky borehole pass-through (inflow of groundwater), a leaky manhole cover or shaft walls (inflow of surface water), or a leak at the fittings (leak in the pipe). Each of these causes requires a different solution. If the shaft is permanently under water, the electrical installation is at risk. Pump out the shaft, identify the source of the water and eliminate the problem. A permanently wet shaft should not be solved by continuous pumping.

What shaft size is sufficient for a family house with average water consumption?

For a family house with 3–5 people, a drilled well and a standard set of fittings (shut-off valve, check valve, water meter, sediment filter), an ideal solution is a shaft with an internal diameter of 1,300 mm and a height of 1,000 mm. This size allows for convenient installation and maintenance, accommodates all fittings without crowding and does not require an excessively large excavation. If you plan to install a filtration unit directly in the shaft or multiple connections, consider a diameter of 1,600 mm. More on dimensioning can be found in the article What shaft size do I need: 1000 vs. 1300 vs. 1600 mm.

Is it necessary to insulate the shaft, or is plastic material sufficient?

Polypropylene plastic has a certain thermal capacity, but it is not an insulator. In areas with harsh winters (Orava, Liptov, mountainous areas of central Slovakia), additional insulation of the interior of the shaft is recommended – either EPS boards glued to the inner wall or closed-cell foam insulation applied to the fittings. Pay special attention to the manhole cover – heat losses mainly occur through the lid. A double-walled cover with internal insulation is an investment that pays off.

Conclusion: a shaft is an investment, not an expense

A shaft for a drilled well is the heart of the entire water supply infrastructure. It is a place where hydraulics, electrical engineering and construction intersect – and where every mistake in design or implementation will eventually show up, usually at the worst possible time (frost, emergency, dug-up garden). Choosing the right dimensions, material, depth of installation and complete set of fittings is not an unnecessary complication – it is the foundation of reliable water supply for decades.

If you are unsure about the choice, take a look at other topics in the Knowledge Centre, for example Installation of a water meter shaft step by step or Common questions about shafts and tanks for home water supplies. Every installation is a bit different, but the principles remain the same – and a well-designed shaft will return to you in peace and reliability at every household tap.

Do you have a question about this topic?

Not sure what to choose or dealing with a specific situation in your home? Write to us – we are happy to help.