SIST EN 18049-1:2026

SLOVENSKI STANDARD
01-december-2026
Vodnjaki - 1. del: Načrtovanje
Water wells - Part 1: Design
Brunnen zur Wassergewinnung - Teil 1: Design
Forages pour l'extraction de l'eau - Partie 1 : Conception
Ta slovenski standard je istoveten z: EN 18049-1:2026
ICS:
93.025 Zunanji sistemi za prevajanje External water conveyance
vode systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 18049-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2026
EUROPÄISCHE NORM
ICS 93.025
English Version
Water wells - Part 1: Design
Forages pour l'extraction de l'eau - Partie 1 : Brunnen zur Wassergewinnung - Teil 1: Design
Conception
This European Standard was approved by CEN on 2 February 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 18049-1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Project objectives . 15
4.1 Background . 15
4.2 Requirement . 15
4.3 Compliance . 15
5 Site conditions . 16
5.1 Background . 16
5.2 Requirements . 16
5.3 Compliance . 16
6 Geological and hydrogeological characterization . 17
6.1 Background . 17
6.2 Requirements . 17
6.3 Compliance . 18
7 Qualitative risk assessment . 19
7.1 Background . 19
7.2 Requirements . 19
7.3 Compliance . 19
8 Estimation of yield . 20
8.1 Background . 20
8.2 Requirement 1 . 20
8.3 Compliance . 20
8.4 Requirement 2 . 21
8.5 Compliance . 21
9 Pump selection . 21
9.1 Background . 21
9.2 Requirement . 21
9.3 Compliance . 21
10 Dimensioning of the well . 23
10.1 General background . 23
10.2 Casing . 26
10.3 Annular space . 27
10.4 Formation stabilizer . 27
10.5 Filter pack (gravel pack) . 28
10.6 Annular seal . 29
10.7 Clay plug and separation filter . 30
10.8 Open area coefficient . 30
10.9 Critical entrance velocity . 31
10.10 Length of screen section . 32
10.11 Sump . 33
11 Selection of materials . 33
11.1 General . 33
11.2 General requirements . 33
11.3 Filter pack. 34
11.4 Casing and screen . 35
11.5 Sealing . 37
11.6 Backfilling material . 38
12 Additional well equipment . 39
12.1 Background . 39
12.2 Requirement 1 . 40
12.3 Compliance . 40
13 Observation wells . 41
13.1 Background . 41
13.2 Requirement 1 . 42
13.3 Compliance . 42
13.4 Requirement 2 . 43
13.5 Compliance . 43
13.6 Requirement 3 . 43
13.7 Compliance . 43
14 Drilling methods . 44
14.1 Background . 44
14.2 Requirement . 44
14.3 Compliance . 44
14.4 Compliance . 45
15 Drilling fluids . 45
15.1 Background . 45
15.2 Requirements . 45
15.3 Compliance . 45
16 Geophysical well logging . 47
16.1 Background . 47
16.2 Well logging methods . 47
16.3 Quality assurance for the performance of well logging measurements . 48
16.4 Design of logging programmes . 48
17 Well Development . 50
17.1 Background . 50
17.2 Requirement 1 . 50
17.3 Requirement 2 . 50
17.4 Compliance . 51
17.5 Requirement 3 . 53
17.6 Compliance . 53
17.7 Requirement 4 . 53
17.8 Compliance . 54
17.9 Equipment . 54
17.10 Specific requirements . 54
18 Pumping test . 55
18.1 Background . 55
18.2 Minimum equipment for the well to be tested . 55
18.3 Location of observations . 55
18.4 Pumping system . 56
18.5 Monitoring equipment . 57
18.6 Performing a pumping test. 58
18.7 Water sampling and analyses . 59
19 Site waste management . 59
19.1 Background . 59
19.2 Requirement 1 . 59
19.3 Compliance . 59
19.4 Requirement 2 . 59
19.5 Compliance . 60
19.6 Requirement 3 . 60
19.7 Compliance . 60
20 Control, maintenance and monitoring . 60
20.1 Background . 60
20.2 Requirement 1 . 60
20.3 Compliance . 60
20.4 Requirement 2 . 61
20.5 Compliance . 61
21 Evaluation of the design . 62
21.1 Background . 62
21.2 Requirement . 63
21.3 Compliance . 63
22 Project design documents. 63
22.1 Background . 63
22.2 Requirement 1 . 63
22.3 Compliance . 63
22.4 Requirement 2 . 63
22.5 Compliance . 64
22.6 Requirement 3 . 64
22.7 Compliance . 64
Annex A (informative) Examples of specific requirements depending on the purpose of the
well . 65
Annex B (informative)  Failure mechanisms and impacts on the surrounding environment
................................................................................................................................................................... 66
Annex C (informative) Submersible pump overall dimensions . 77
Annex D (informative) Criteria for selection of the drilling method and specification of
drilling methods . 78
D.1 Purpose of well . 78
D.2 Kind of rock . 78
D.3 Planned depth . 79
D.4 Necessity to collect reliable rock samples . 79
D.5 specification of the drilling methods . 79
Annex E (informative) Terms, symbols, units and abbreviations of major logging techniques
................................................................................................................................................................... 84
E.1 Terms, symbols, units and abbreviations of major logging methods . 84
E.2 Logging programmes for open, temporarily cased/partially cased boreholes in
unconsolidated rock – Recommended logging programmes . 86
E.3 Logging programmes for open, temporarily cased/partially cased boreholes in
consolidated rock – Recommended logging programmes . 87
Bibliography . 90

European foreword
This document (EN 18049-1:2026) has been prepared by Technical Committee CEN/TC 451 “Water wells
and borehole heat exchangers”, the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2027, and conflicting national standards shall be
withdrawn at the latest by October 2029.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Within its program of work, Technical Committee CEN/TC 451 requested CEN/TC 451/WG 1 “water
wells” to prepare the following standard:
EN 18049-1, Water wells — Part 1: Design.
The EN 18049 series under the main title water wells will consist of the following parts:
— Part 1: Design;
— Part 2: Construction;
— Part 3: Operation and abandoning.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
1 Scope
This document is applicable to all types of water wells, whether for public or private use, abstracting from
or injecting water to the groundwater, in a variety of applications. These include potable water
abstraction, industrial use, irrigation, dewatering, aquifer recharge, and geothermal applications, or for
groundwater observation (see Clause 13).
This document does not apply to horizontal wells, groundwater quality monitoring wells in potentially
contaminated sites, and closed loop geothermal systems.
This document defines design requirements of water wells for public and private users in accordance
with groundwater protection goals. It gives guidelines for all planning steps from preliminary to final
executive project design.
A sequential method for designing and dimensioning a well is specified. Based on the hydrogeological
conditions and the objectives of the well, a step-by-step process for dimensioning the well is defined. This
methodology includes dimensioning for the drilling, filter packs, sealings and screens. Furthermore,
selection of appropriate materials, the pump and all other additional well equipment is outlined. With
regard to the planning process references are provided for drilling methods, geophysical well logging,
well development and pumping tests.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 14396:2004, Fixed ladders for manholes
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
abandoned well
well which is decommissioned, a term used when a well’s use is permanently discontinued or if it is in a
condition that makes it uneconomic to repair
3.2
alignment of the well
measure of the straightness of adjacent sections of a well
Note 1 to entry: Often tested by running a dummy tool into the well.
3.3
annular space (annulus)
space between a drilled hole and the well casing
3.4
aquifer
water-bearing geological layer comprising permeable rock, fractured rock or unconsolidated materials
(gravel, sand, or silt)
3.5
aquifer stimulation
type of development that is carried out to alter the formation physically to improve its hydraulic
properties
3.6
aquifer test
special case of a pumping test often using additional observation wells to obtain information about the
characteristics of an aquifer
3.7
aquitard
geologic formation having very low permeability
Note 1 to term: An aquitard with extremely low permeability can be termed aquiclude.
3.8
artesian aquifer
confined aquifer in which the piezometric surface is above the ground level
3.9
artesian well
free flowing well
wells (bore holes) that penetrate artesian aquifers
3.10
auger
machine having a rotating helical shaft for boring into the earth
3.11
bailer
cylindrical, bucket-like device with a footvalve used to collect or remove mud and rock cuttings from the
borehole
3.12
borehole
hole created by drilling into the ground
3.13
bottom hole assembly
lower portion of the drill string, which can consist of (from the bottom up) the bit, bit sub, a mud motor
(in certain cases), stabilisers, drill collars, heavyweight drill pipe, jarring devices (jar) and crossovers for
various thread forms
3.14
cable tool
group of machines for drilling by the breaking and crushing action of heavy drilling tools suspended on a
cable which are repeatedly lifted and dropped
3.15
casing
tube (usually steel or plastic) that is installed in a well to maintain the well opening and to provide a seal
3.16
cementing
specific case of grouting where only cement and water are used
3.17
centralisers
devices used to ensure that casing or riser tubes are installed centrally within the borehole
3.18
confined aquifer
aquifer whose upper and lower boundaries are low permeability layers which confine the groundwater
under greater than atmospheric pressure
3.19
core
continuous cylinder of rock, cut from the bottom of a borehole as a sample of an underground formation
3.20
cuttings
small pieces of rock or broken material derived from the drilling process, which can be used for sampling
3.21
down-the-hole hammer
DTH
self-rotating air-activated percussive drilling bit
3.22
drawdown
decrease in ground water level caused by pumping, measured as the difference between the static and
the dynamic water level at a particular time
3.23
drill bit
cutting tool used in well drilling
3.24
drilling additives
drilling fluid additives
drilling mud additives
specific components of the drilling fluid that can be used to restore the drilling mud properties or to act
in a particular way as required
3.25
drill collar
component of a drill string that provides weight on the bit for drilling
3.26
drill pipe
steel pipe used to carry and rotate the drilling tools in a well, and to permit the circulation of drilling fluid
3.27
drilling fluid
drilling mud
water or air-based fluid used in the water well drilling operation to remove cuttings from the hole, to
clean and cool the bit, to reduce friction between the drill string and the sides of the hole, and to seal the
borehole
3.28
dynamic water level
piezometric surface influenced by pumping or injection, as opposed to the static water level (3.63)
Note 1 to entry: More specifically, drawn down or raised water level, whether or not stabilized, in a pumping well
or injection structure
3.29
filter cake
suspended solids that are deposited on a porous medium during the process of filtration
3.30
free flowing well
(see artesian well)
3.31
formation
general term for the geological units surrounding the borehole
3.32
formation stabiliser
sand or gravel placed in the annulus of the well between the borehole wall and the well screen and casing
to provide temporary or long-term support for the borehole
3.33
geophysical well logging
terminology for a suite of technologies that indicate absolute or relative properties of geological
formations, aquifers and wells
3.34
filter pack
gravel pack
coarse sand, fine gravel, glass beads, or other suitable materials, that are placed between the borehole
wall and screen to retain the formation and improve the hydraulic condition around the well
3.35
grout
cement- and/or clay-based sealing material (e.g. swelling clay) used to create a sanitary seal in the
annular space to prevent crossflow between aquifers and/or contaminants from entering the well
3.36
hydraulic head loss
energy loss within a fluid system, e.g. due to friction or turbulence, as water moves from an aquifer
through the well (filter pack, screen, pump, riser pipes) to the surface
3.37
hydraulic conductivity
capacity of subsurface materials (sand, rock etc.) to allow a fluid (i.e. water) to flow through it. For an
isotropic porous medium and homogenous fluid, the volume of water that moves in unit time under a
unit hydraulic gradient through a unit area measured perpendicular to the direction of flow
3 2
Note 1 to entry: In the SI System, the units are m /s/m or m/s.
3.38
hydraulic head [m]
height above a datum plane (such as sea level) of the top of the column of water that can be supported by
the hydraulic pressure at a given point in a ground water system. For a well, the hydraulic head is equal
to the distance between the water level in the well and the datum plane
3.39
impermeable
resistant to flow of or penetration by water or other liquids
3.40
injection well
well constructed for the purpose of injecting water directly into the aquifer
3.41
infiltration well
well constructed for the purpose of allowing water to flow into the aquifer under the force of gravity
3.42
kelly
long square or hexagonal steel bar connecting the rotary table with the drill string enabling rotary
motion, while allowing the drill string to be lowered or raised during rotation
3.43
managed aquifer recharge
MAR
managed aquifer recharge (MAR) is the artificial recharge of water into aquifers for subsequent recovery
or environmental benefit
Note 1 to entry: MAR can include many techniques, such as Aquifer Storage and Recovery (ASR) for example.
3.44
monitoring well
well constructed or used for the purposes of water level or water quality data collection
Note 1 to entry: Monitoring wells are often installed to provide an early warning of contamination occurring down
gradient from a landfill or industrial facility. See also Observation wells.
3.45
observation well
well constructed in a specific location for the purpose of observing(measuring) changes in water level
Note 1 to entry: An existing well perhaps drilled for a different purpose may also be used to observe water level
changes. Observation wells are typically used for short duration data collection such as before, during and after an
aquifer test. Wells that are used to collect data on a long term basis are usually referred to as monitoring wells.
3.46
packer
device used to isolate particular portions of the aquifer in a borehole
3.47
partial penetration
when the depth of the intake portion of the well is less than the full thickness of the aquifer
3.48
piezometer
small diameter monitoring well used for water level observation (see monitoring well)
3.49
polymer mud
water based drilling fluid with polymers
3.50
porosity
property of a rock or soil containing interstices or voids, expressed as a ratio of the volume of the voids,
connected or isolated, over the total volume
Note 1 to entry Porosity can be intergranular or fissured and is responsible for storage capacity as well as
hydraulic conductivity. In hydrogeology, effective porosity (also called drainage porosity) refers to connected
interstices where water can be moving and being drained out from a sample.
3.51
production well
water well designed to meet a particular demand of groundwater
3.52
pumping test
controlled pumping with associated measurements of water level changes that are used to determine
aquifer characteristics and the hydraulic properties of wells
3.53
rig
the machine used to drill a well
3.54
rising main
drop pipe
pump column
pipe connecting the submersible pump to the wellhead
3.55
rotary table
revolving section of the drill floor that provides torque to rotate the drill string
Note 1 to entry: The rotary motion and power are transmitted through the kelly bushing and the kelly to the drill
string
3.56
saline intrusion
entry of saline water into an aquifer
3.57
saline water
salt water
water that contains high concentrations of dissolved solids, mainly sodium chloride
3.58
screen
well screen
slotted tube or wire wound screen usually made of steel or plastic material with apertures used to allow
water to enter a well while preventing sediment or rock particles from entering the well
3.59
sieve analysis
determination of the particle-size distribution of a soil, sediment, or rock by measuring the mass of the
particles that will pass through a standard set of sieves and reporting the results as the percentage
retained or passing
3.60
sinkhole
depression in the land surface caused by collapse of overlying soils or rock into pre-existing cave systems,
usually in areas of limestone geology
3.61
slurry
thin mixture of liquid, especially water, and any of several finely divided substances, such as cement or
clay particles, but capable of pumping
3.62
specific capacity
rate of discharge of a well per unit depth of drawdown. It is used as a measure of well efficiency. The ideal
for a well is high discharge and low drawdown
3 2
Note 1 to entry Units are m /s/m or m /s.
3.63
static water level
static or rest water level is the level at which water stands in a well when the water level is at equilibrium
with atmospheric pressures when it is neither under the influence of pumping nor injection
Note 1 to entry: It is a measure of the depth from the ground surface or from a known reference point to the water
level. The water level may also be measured relative to a datum such as sea level (see also, dynamic water level)
3.64
subsidence
dropping of the land surface for example as a result of over-pumping ground water. Cracks and fissures
can appear in the land
Note 1 to entry: Subsidence is usually an irreversible process.
3.65
suspended solids
soil particles that remain in suspension in water for a considerable period of time without falling to the
bottom under the force of gravity
Note 1 to entry: Such material remains in suspension due to the upward components of turbulence and currents
and/or by suspension.
3.66
test well
exploratory borehole
well used to assess and/or test the geologic and hydraulic properties of an aquifer
Note 1 to entry: A series of test wells can be drilled in order to determine the most effective location for a (much
more expensive) production well
Note 2 to entry: Test wells are usually of a smaller diameter than production wells.
3.67
top drive drilling
drilling rotary method in which the rotary motion is provided by a mechanical device (hydraulic pressure
head) located at the swivel and which moves vertically up and down the mast. It is a recent alternative to
the rotary table and kelly drive
3.68
transmissivity
rate at which groundwater can flow through an aquifer section of unit width under a unit hydraulic
gradient. It is the average hydraulic conductivity of a section of the entire aquifer at a given location
multiplied by the thickness of the producing formation
2 2
Note 1 to entry: SI-Units are m /s, sometimes expressed as m /day.
3.69
tremie pipe
pipe used to carry materials (usually grout) to a specific depth in a drilled hole. Tremie pipes are slowly
withdrawn as the grout is placed in the well
3.70
unconfined aquifer
aquifer with an upper surface as a water table whose piezometric surface is at atmospheric pressure (an
unconfined surface)
Note 1 to entry: The level of this groundwater can fluctuate, creating a saturated zone and an unsaturated zone
3.71
uniformity coefficient
d /d
60 10
ratio used to characterise a sediment using a plotted grain-size distribution curve, derived from sieving.
It is the 60% passing size (d ) divided by the 10% passing size (d )
60 10
3.72
verticality
deviation from an imaginary vertical line from the ground surface to the centre of the earth
Note 1 to entry: Usually measured in meters or centimeters.
3.73
water table
surface of a body of unconfined groundwater at which the pressure is equal to that of the atmosphere.
The static water level in a well in an unconfined aquifer
3.74
well development
application of techniques after and during the drilling process that bring the well to its maximum yield
capacity and achieve maximum well efficiency
3.75
well yield
volume of water discharged from a well in SI-Units m /s, often expressed in litres per second (l/s)
3.76
wellhead
equipment/installation used to maintain surface control of a well and prevent ingress of contamination
4 Project objectives
4.1 Background
Before starting the design of a well or well field, there needs to be an agreement between the
commissioning party and the designing party with respect to the objectives of the project.
These objectives form a framework for the entire design process, including the evaluation of the design
at the end of the design process to check whether the design meets the project objectives (as explained
in Clause 21) and the construction of the work. Secondly, the requirements form the basis of a contract
between the commissioning party and the designing party. Thus, they also serve as protection for the
customer, especially those that are not very familiar with the design of wells. Finally, the requirements
may also be used for communication with third parties who depend on the design of the well. For
example, the well discharge may be the important input for a company that is responsible for the
transmission of pumped water above ground surface.
4.2 Requirement
Identification of the location and objectives of the well as well as for the timeframe of the project.
4.3 Compliance
These following aspects shall be formulated in a document, such as a specification sheet or tender
document. Both design and commissioning party shall go through the document and agree consensually
on it.
— The location of the well. This shall either be defined in the form of georeferenced discrete point or as
an area for the project defined as a polygon of georeferenced points.
— The purpose of the well: for pumping, injection, infiltration, or as an observation well.
— The required flowrate and/or required water level. This shall be defined as a discrete number or as
a range.
— The theoretical minimum technical life span for the well.
— The minimum desired raw water quality properties of the abstracted water. These shall be in line
with the purpose of the well, the local regulations and other requirements of the commissioning
party.
— Interface with the above-ground installation. For example, the water pressure and pipe diameter at
the wellhead.
— Check if additional requirements arise from an existing legal framework
— Check if there are additional requirements, depending on the purpose of the well (see examples in
Annex A).
— A concrete time schedule or at least a timeframe. The time schedule shall at least indicate when the
wells shall be drilled and when they shall be operational, and address both the dimension and
complexity of the project.
5 Site conditions
5.1 Background
Encountering unanticipated site conditions leads to i
...