SIST EN 1508:2025

SLOVENSKI STANDARD
01-december-2025
Oskrba z vodo - Zahteve za sisteme in sestavne dele vodnih zbiralnikov
Water supply - Requirements for systems and components for the storage of water
Wasserversorgung - Anforderungen an Systeme und Bestandteile der
Wasserspeicherung
Alimentation en eau - Prescriptions pour les systèmes et les composants pour le
stockage de l'eau
Ta slovenski standard je istoveten z: EN 1508:2025
ICS:
91.140.60 Sistemi za oskrbo z vodo Water supply systems
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 1508
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 93.025 Supersedes EN 1508:1998
English Version
Water supply - Requirements for systems and components
for the storage of water
Alimentation en eau - Prescriptions pour les systèmes Wasserversorgung - Anforderungen an Systeme und
et les composants pour le stockage de l'eau Bestandteile der Wasserspeicherung
This European Standard was approved by CEN on 1 September 2025.

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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1508:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Abbreviated terms . 9
5 General requirements . 9
5.1 General. 9
5.1.1 General. 9
5.1.2 Functions . 9
5.1.3 Decision criteria and system configuration . 9
5.2 Functional requirements . 10
5.2.1 Functional requirements – water quality . 10
5.2.2 Functional requirements – operation . 12
6 Design requirements . 15
6.1 Design general – volume, elevation . 15
6.1.1 Type of service reservoirs . 15
6.1.2 Operational water level . 15
6.1.3 Capacity and exchange of water . 16
6.1.4 Physical shape of water compartments . 17
6.1.5 Materials . 17
6.1.6 Piping within service reservoirs . 17
6.1.7 Safe working conditions for operation and maintenance . 17
6.2 Watertightness . 17
6.3 Structural design . 18
6.3.1 General. 18
6.3.2 Limit states . 18
6.4 Further provisions. 19
6.4.1 Stress analysis . 19
6.4.2 Stress analysis – construction . 19
6.4.3 Stress analysis – water towers . 19
6.4.4 Crack width . 20
6.4.5 Drainage . 20
6.4.6 External roofs . 20
7 General requirements for products . 20
8 Commissioning, tests and checks . 20
8.1 General considerations . 20
8.1.1 General. 20
8.1.2 Hygiene . 20
8.1.3 Safety of personnel . 21
8.1.4 Principles . 21
8.1.5 Roofs . 21
8.1.6 Walls and floors . 22
8.2 Cleaning and disinfection . 23
8.2.1 General . 23
8.2.2 Cleaning . 23
8.2.3 Disinfection . 23
8.2.4 Water quality clearance . 23
8.2.5 Records . 24
8.3 Commissioning . 24
8.3.1 General . 24
8.3.2 Water quality. 24
8.3.3 Operations . 24
9 Operational requirements . 24
9.1 Introduction . 24
9.1.1 General . 24
9.1.2 Monitoring. 24
9.1.3 Inspection . 24
9.1.4 External inspection . 25
9.1.5 Operating manual . 25
9.2 Maintenance . 25
9.3 Cleaning and disinfection . 25
10 Rehabilitation and repair requirements . 25
10.1 Introduction . 25
10.2 Survey . 25
10.3 Prevention of contamination . 26
10.4 Return to service . 26
Annex A (informative) Guidance to EN 1508 . 27
Bibliography . 41

European foreword
This document (EN 1508:2025) has been prepared by Technical Committee CEN/TC 164 “Water supply”,
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 2026, and conflicting national standards shall be
withdrawn at the latest by April 2026.
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.
This document supersedes EN 1508:1998.
— improvements related to the long-term resilience and security of drinking water storage and demand
management;
— clarification of terms used to describe different types of pumped or gravity fed reservoirs;
— improved and updated figures;
— addressing innovations in ventilation and air control;
— new Clause A.8 added, giving guidance on the selection of ventilation systems;
— new Clause A.9 added, showing a typical inspection checklist.
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.
Introduction
In specifying the requirements of this document, due regard has been taken of the importance of a reliable
and safe supply of water for human consumption as well as for the purpose of trade, industry, agriculture
and firefighting.
This document is written for the designer, owner, operator and contractor.
The contractor can be the builder or be performing maintenance, cleaning and inspection.
The widely varying water supply legislative requirements, populations, social and climatic conditions
have also been taken into account.
It is not intended that existing reservoirs are altered to comply with this document, provided that there
are no significant detrimental effects on water quality.
1 Scope
This document specifies and gives guidance on:
— general requirements for storage of water outside consumers' buildings, including service reservoirs
for potable water and reservoirs containing water not for human consumption at intake works or
within treatment works, excluding those that are part of the treatment process;
— design;
— general requirements for product standards;
— requirements for quality control and auditing, testing and commissioning;
— operational requirements;
— requirements for inspection, rehabilitation and repair.
The requirements of this document are applicable to:
— design and construction of new reservoirs;
— extension and modification of existing reservoirs;
— significant rehabilitation of existing reservoirs.
This document does not apply to reservoirs formed by the building of dams or the use of lakes for water
storage purposes.
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 805, Water supply — Requirements for systems and components outside buildings
EN 1992-1-1, Eurocode 2 — Design of concrete structures — Part 1-1: General rules and rules for buildings,
bridges and civil engineering structures
EN 15975-1, Security of drinking water supply — Guidelines for risk and crisis management — Part 1: Crisis
management
EN 15975-2, Security of drinking water supply — Guidelines for risk and crisis management — Part 2: Risk
management
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:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
air tightness
characteristic quality of the structure that prevents the passage of air through the structure in other ways
than the intended route
3.2
capacity
volume of the compartment(s) that can be used for the operation of a reservoir
3.3
equalization volume
volume used to equalize the incoming water flow to the outgoing water flow of the reservoir during day
and night
3.4
emergency volume
volume for demands during emergency situations
Note 1 to entry: Examples of emergencies are breaks of water mains, pump failures, water treatment plant
interruptions, etc.
3.5
firefighting volume
volume for water demand for firefighting
3.6
dead volume
volume which cannot be used because it is below the level of the entrance to the outlet pipe or is below
the minimum acceptable hydraulic gradient
3.7
compartment
self-contained part of a reservoir which has separate inlet, outlet, overflow and washout arrangements,
and can be operated independently from other compartments of the same reservoir
Note 1 to entry: See Figures 1 and 2.
3.8
control building
self-contained part of a reservoir used to accommodate the main valves, pumps, controls and monitoring
equipment and which can provide the means of access to the water compartment(s)
3.9
critical point
point in the water distribution system whose minimum allowable pressure determines the location and
elevation of the service reservoir
3.10
designer
person responsible for establishing, with the purchaser or water company, the basic criteria to be used
for the design, construction, commissioning and operation of the reservoir
3.11
rehabilitation
work necessary to upgrade or improve a reservoir
3.12
repair
work necessary to remedy a defect and restore a reservoir to satisfactory operation
3.13
reservoir
storage facility for water
Note 1 to entry: Examples for reservoirs are service reservoirs, artificial lakes and natural lakes whose outlet has
been dammed to control the water level. In the document, both terms reservoir and service reservoir are used but
the document does not apply to reservoirs like lakes or dams.
3.14
service reservoir
covered storage facility for potable water which includes water compartment(s), control building,
operation equipment and access arrangements, providing reserve supplies and pressure stability, and
balancing demand fluctuations
Note 1 to entry: See Figure 1.
Note 2 to entry: Service reservoirs can be operated with or without pumping stations.
Note 3 to entry: In English literature and in common practice the term tank is also used.
3.15
ground service reservoir
service reservoir whose bottom of the water volume is at or near ground level
3.16
buried service reservoir
service reservoir whose top of the water volume is at or near ground level
3.17
water demand
estimated quantity of water required per unit of time
3.18
water tightness
characteristic quality of the structure that prevents the passage of water through the structure in excess
of any permitted quantity
3.19
water tower
reservoir constructed with the compartment(s) above ground level with an elevation sufficient to provide
water by gravity to the supply area
Note 1 to entry: In the literature and in common practice, the terms elevated tank and elevated service reservoir
are also used.
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
CFD computational fluid dynamics
WSA water supply area
5 General requirements
5.1 General
5.1.1 General
This document is written principally for application to service reservoirs. In the case of other reservoirs,
this document can be used as guidance with only relevant parts applied, for example disinfection is not
always required for reservoirs containing water not for human consumption.
Guidance on the application of this document is provided in Annex A.
NOTE Potentially relevant general requirements for systems and components can be found in Directive (EU)
2020/2184 [1], which concerns the quality of water for human consumption.
5.1.2 Functions
The purpose of service reservoirs is to store the necessary amount of water required for water supply in
the area concerned. To achieve this their functions, include:
a) to equalize the difference between water intake and output and to cover peaks in demand;
b) to maintain the required pressure in the water distribution systems;
c) to keep stocks in reserve in case of plant malfunctions and interruptions in the water distribution
systems;
d) to provide water for firefighting, taking into account local requirements.
See also A.1.
5.1.3 Decision criteria and system configuration
Important decision criteria are:
a) security of supply and water quality;
b) overall cost of construction, operation and maintenance;
c) integration into the water supply system;
d) town and landscape planning;
e) system resilience, for example multiple compartments to enable inspection and maintenance
without interruption of services;
f) pipework constraints, for example separate inlets and outlets or common pipework;
g) expected duration of planned and unplanned maintenance.
The above-mentioned criteria can be achieved by elevated service reservoirs, water towers or by low
level service reservoirs with pumping systems. Service reservoirs can be designed as buried, partially
buried or above ground structures.
The construction of an elevated service reservoir is advisable if suitable high ground is available.
The construction of a water tower may be considered where the necessary ground elevation at a suitable
point near the supply area is not available for an elevated service reservoir.
A pumping station with a low-level service reservoir is a viable option if measures have been taken to
ensure continuity of power supply.
Service reservoirs are mainly constructed from reinforced, pre-cast or pre-stressed concrete. They may
also be constructed using steel, glass fibre reinforced plastic or other materials that fulfil the
requirements of this document.
See also A.2.
5.2 Functional requirements
5.2.1 Functional requirements – water quality
5.2.1.1 General
Service reservoirs shall be designed, constructed and operated to prevent contamination or other
chemical, physical and biological changes that are detrimental to the water quality.
Hydraulic modelling can be used to determine where in the distribution network to place a reservoir and
the necessary height.
NOTE Service reservoirs and their components can be subject to European, national or local laws, regulations,
directives, standards and technical approvals, in particular concerning water quality.
5.2.1.2 Materials
Materials which meet test requirements as specified in relevant product standards and codes of practice
and will not cause the stored water to deteriorate shall be used in the structure of the water
compartments and on the surfaces in contact with the stored water.
Concrete and cement mortars generally satisfy this requirement, but special care shall be taken if
additives are used. In order to facilitate subsequent cleaning and to avoid bacterial growth internal
surfaces shall be as smooth and pore-free as possible.
This can be achieved by high quality concrete finishes including form work liners or by the application of
suitable coatings or linings. It shall be verified that materials such as applied coatings do not increase
microbial growth, release of chemical contaminants or break down.
All metallic parts to be installed within the compartments shall be protected, stainless steel is
recommended.
The designer should consider materials and the chemical properties of water being stored and be durable
against chemical attack (e.g. soft water).
5.2.1.3 Water circulation
Stagnant zones shall be minimized. This can be achieved by suitable design of the physical shape of the
water compartments and the arrangement of inlet and outlet pipework for the particular storage capacity
and operating procedures. The capacity of a service reservoir shall not be larger than the sum of the
equalization volume, the emergency volume and the firefighting volume. Any larger volume will lead to
higher risk for stagnant zones and longer retention time in the service reservoir.
For service reservoirs, the design can be undertaken using computational fluid dynamics (CFD) or
physical modelling under operating conditions to ensure circulation.
In reservoirs with separate inlet and outlet pipework it is important to design the pipework to avoid short
circuits.
Valves should be positioned on pipework so that water does not stagnate within the pipework. For
example, the washout valves should be positioned as close as possible to the drainage sump.
5.2.1.4 Ventilation
Ventilation facilities are required in the water compartments in order to permit air movement caused by
changing water levels. This can be achieved by natural or forced ventilation. The water compartment
shall not be placed at operational risk by negative pressure caused by impairments of the ventilation
equipment (e.g. clogging of the screens/filters). Therefore, corresponding predetermined breaking
points or safety valves shall be provided in the ventilation system. The designer shall specify the
measures to be taken to safeguard and control the quantity and quality of the air entering and quantity
of the air leaving the service reservoir.
Reservoirs shall be protected from negative pressures as a result of water draining when the ventilation
is reduced.
The ventilation of any associated facilities should be separated from the ventilation of the water storage
compartments.
NOTE Local regulations can specify a type of air filter.
A.8 provides guidance for selecting the ventilation systems that are available for different types of
reservoirs.
5.2.1.5 Prevention of contamination
Service reservoirs shall be designed to prevent the ingress of external water or other contaminant either
through the structure of any opening, entrance or pipework. Permanent exposure of the water to daylight
shall be avoided.
Entrances and ventilation equipment shall also be designed so that the water cannot be contaminated
(e.g. by polluted air, dust, insects and other animals, human interference, deliberate or otherwise). Care
shall be taken to prevent air from coming into the compartment in other ways than the intended.
Design may specify that openings will not be positioned directly above the free water surface. Ventilation
openings should be placed above the overflow if possible. Wherever positioned they shall be arranged in
such a way that no extraneous matter is able to enter the compartment and that all external interference
is impeded.
5.2.1.6 Temperature effects
There shall be no unacceptable alteration to the stored water caused by heat or cold. Thermal insulation
measures can be necessary to avoid adverse effects on the stored water, the structure and the associated
equipment. The thermal insulation measures for service reservoirs shall be appropriate for the local
climatic conditions, the operating requirements and in order to minimize condensation within the water
compartments.
The designer shall consider the changes in temperature resulting from climate change.
5.2.1.7 Maintaining water quality
Service reservoirs are expected to maintain the water quality throughout their operational cycle and
asset life.
Prior to commissioning or following internal maintenance, the service reservoir and the associated
equipment shall be carefully checked then cleaned and disinfected if necessary.
Inspections shall be carried out before initial commissioning, during operation and as part of regular
maintenance.
Facilities to allow the sampling of water, without entry by personnel, shall be provided. There shall be at
least one sampling point for each compartment and for the inlet and outlet pipes.
Emptying of the service reservoir should be possible.
NOTE Emptying of the service reservoir is useful in case the water quality falls below or does not meet the
requirements of the relevant drinking water regulations.
5.2.2 Functional requirements – operation
5.2.2.1 Access and security
Service reservoir sites shall be provided with access for routine visits and repair work. Facilities shall be
provided to permit cleaning of each compartment independently.
Access to the water compartments, control buildings and all functional equipment shall be designed for
safety, including that of personnel, and for ease of operation. Openings shall be dimensioned so as to
permit entry for materials and equipment for cleaning, maintenance and repair. Care should be taken
regarding the placement of manholes to ensure safe working conditions when access to the
compartments is needed. Access to the reservoirs shall always be restricted and controlled.
Arrangements shall be such that the minimum number of openings are provided into the water
compartments. The compartments may be accessed from the control building or, subject to suitable
safeguards, from the roof.
Due regard shall be paid to the security of service reservoirs with respect to acts of terrorism, vandalism
and other unlawful activity. Measures shall be taken to deter, detect and delay intruders (e.g. property
protection such as alarm systems, video surveillance, motion detectors).
The preparation of a safety concept with hazard analysis, risk assessment, the implementation of
measures to control risks and to achieve the required protection level shall be carried out in accordance
with EN 15975-1 and EN 15975-2.
See also A.3.
5.2.2.2 General arrangement
Service reservoirs should normally comprise at least two compartments (see Figure 2).
Inlet, outlet, overflow and washout pipework, the necessary valves, and if specified by the designer, flow
meters and level measuring devices, shall be provided for each water compartment.
A bypass pipework arrangement to connect inlet and outlet pipework should be provided where
appropriate. Where provided, the bypass pipework shall be designed to avoid stagnation and reduced
water quality. Any connection between inlet and outlet should be sized for full flow. The type and
arrangement of the valves will depend upon the configuration of the water distribution system.
If necessary, underfloor and perimeter drains shall be provided.
Any control room shall be fully separated from the water storage compartments by a solid wall and
contain a sump for a temporary pump or connected to the drainage system.
NOTE Bypass pipework is not always necessary on water treatment works disinfection contact tanks.
5.2.2.3 Overflow and washout
The overflow of each compartment shall be of dimensions that permit the free escape of excess water and
should allow for the discharge of the maximum inflow capable of being delivered to the service reservoir.
Hydraulic modelling can be used to estimate the maximum inflow.
There shall be no isolation valves on the overflow system.
The overflow arrangements shall not permit the contamination of the stored water.
If the overflow level is below ground level protective measures shall be taken to prevent contamination
through the overflow.
The overflow and washout should not be permanently connected to a sewer except where this is
unavoidable. Special attention shall be given to checking the capacity of the sewer, providing an air gap
and a water trap to prevent the backflow of foul water and gases from the sewer.
Where discharging into a watercourse, de-chlorination chambers should be considered.
5.2.2.4 Monitoring
Service reservoirs shall be monitored and controlled. All necessary operational data shall be recorded.
The designer shall specify if visual inspection facilities are required to observe the water in each
compartment.
See also A.4.
5.2.2.5 Power supplies
Consideration shall be given to providing permanent and emergency power supplies to service reservoir
sites.
5.2.2.6 Lightning protection
Lightning protection arrangements shall be provided for all water towers and shall be considered for all
service reservoirs.
Key
1 compartment 13 max. water level
2 control building 14 level at max. overflow
3 inlet system fills the reservoir under 15 sump
the water level
4 inlet system fills the reservoir above 16 sloping floor
the water level
5 outlet 17 ventilation with filter (optionally extended
to compartment)
6 washout 18 ventilation of the compartment
7 bypass valve 19 underfloor drains (if required)
8 overflow 20 perimeter drain (if required)
9 strainer (if required) 21 membrane/roof topping
10 capacity 22 roof drainage
11 max. water depth 23 pipe system for roof drainage
12 max. operation water level 24 points for sampling
Figure 1 — Simplified section through service reservoir
Key
1 compartment 1 6 washout
2 compartment 2 7 bypass valve
3 inlet 8 from treatment works or source
4 outlet 9 washout/overflow
5 overflow 10 to supply area
11 points for sampling
Figure 2 — Simplified arrangement of service reservoir
6 Design requirements
6.1 Design general – volume, elevation
6.1.1 Type of service reservoirs
The elevation of ground and buried service reservoirs should be chosen to be sufficient to provide water
by gravity to the supply area where possible. If there is no convenient high ground, the solutions are
water towers and ground or buried service reservoirs with pumping stations.
6.1.2 Operational water level
With the location taken into consideration, the reservoir shall be designed so that the requirements for
minimum pressure are fulfilled at the critical point in the service area at the lowest operational water
level in the service reservoir, see Figure 3.
The maximum allowable pressure shall not be exceeded at the lowest placed facility within the service
area while at the highest operational water level in the service reservoir.
If pumps are used to distribute water from a reservoir the lowest operational level in the reservoir shall
be considered when pumps are installed.
а) at the beginning of the water supplied area

b) at a hill inside of the water supplied area

c) at the end of the water supplied area
Key
1 head at the critical point
2 hydraulic gradient
3 service reservoir
4 water distribution network of the water supply area
Figure 3 — Different cases of a location of the critical point
If pumps are used to distribute water from a reservoir, the lowest operational level in the reservoir shall
be considered when pumps are specified.
6.1.3 Capacity and exchange of water
The capacity should be the sum of equalization volume, emergency volume and firefighting volume.
The designer shall consider the need for:
a) equalization volume;
b) emergency volume;
c) firefighting volume;
d) dead volume.
The retention time in the reservoir should be as short as possible to prevent the deterioration of the water
quality.
6.1.4 Physical shape of water compartments
The water compartment(s) should be designed either for plug flow or complete mixing. Plug flow is
preferable for service reservoirs at the water works where a contact time for disinfection is needed. For
service reservoirs within water distribution systems, complete mixing is preferable.
6.1.5 Materials
The designer should be aware that decisions on the materials used for construction and any lining will
affect other design factors such as the need for thermal isolation or suitable floor slope.
6.1.6 Piping within service reservoirs
Installations of pipes directly on the floor should be avoided in the water compartments. Pipes should
always be installed on piers.
Valves should be placed outside the water compartments.
Drainpipes from the roof shall be placed outside the water compartments to avoid contamination from
rainwater in case of blockage of drainpipes. The roof drainage shall be connected to a drain separated
from the underdrainage and back- of-wall drainage.
Piping in the service reservoir is shown in Figures 1 and 2.
6.1.7 Safe working conditions for operation and maintenance
The designer shall consider how to ensure safe working conditions during operation and maintenance.
Hatches to enter the reservoir from the roof shall not be placed at the outer edge of the roof of ground
reservoirs and water towers.
6.2 Watertightness
Reservoirs shall be designed to be watertight. This can be achieved using various methods, either singly
or in various combinations as described below:
a) structures where watertightness is obtained by the nature of the structure itself, which is typically
achieved by reinforced, precast concrete or prestressed concrete structures. The water tightness
class required shall be determined by the designer in accordance with EN 1992-1-1. In addition, it is
possible to improve the impermeability of the concrete by the inclusion of additives or the
application of surface treatments;
b) structures where watertightness is achieved by the structure itself, and to which a coating has been
added;
c) structures where watertightness is achieved by the addition of a waterproof coating or lining which
can either be bonded to or independent from the supporting structure.
For structures using prefabricated component parts, watertightness can be achieved using the above
techniques.
Special attention shall be paid to construction and movement joints, pipes or ducts passing through
structural elements and other features subject to water pressure. This shall include the use of water stops
and sealants.
6.3 Structural design
6.3.1 General
In all aspects, including health and safety during construction, the valid national design and construction
standards and requirements at the place where the reservoir is proposed to be constructed and the
relevant structural Eurocodes apply. The structural design shall be based on the acceptable probability
that the service reservoir will remain fit for the use for which it is intended throughout its design life. This
involves calculation at limit states.
6.3.2 Limit states
6.3.2.1 General
Ultimate limit states which require consideration include:
a) loss of equilibrium of the structure or any part of it, considered as a rigid body;
b) failure by excessive deformation, rupture, or loss of stability of the structure or any part of it,
including supports and foundations.
Serviceability limit states which require consideration include:
a) deformations or deflections which affect the appearance or effective use of the structure (including
the malfunction of machines or services) or cause damage to finishes or non-structural elements;
b) cracking which is likely to affect adversely the appearance, durability or watertightness of the
structure;
c) vibration which causes discomfort to people, damage to the service reservoir or to its components,
or which limits its functional effectiveness;
d) excessive stress which is likely to lead to loss of durability.
The structural design shall take into account the effects of permanent, variable and accidental actions.
The reservoir and its compartments shall be designed for both the full and empty conditions.
6.3.2.2 Permanent actions
Permanent actions include:
a) the dead load of the structure;
b) the load of the operational equipment and plant (e.g. pumps and pipework);
c) the load of any additional installations;
and, where applicable:
d) the prestressing load;
e) the earth load and earth pressure;
f) the load and pressure of the groundwater at its lowest assumed level;
g) any imposed displacement;
h) shrinkage;
i) creep.
6.3.2.3 Variable actions
Variable actions include:
a) the load and pressure of the water in the reservoir;
b) the snow and wind loads;
c) the loads due to operation of the reservoir;
d) the loads due to maintenance;
and, where applicable:
e) the load and pressure of the groundwater at its highest assumed level;
f) transient loads in the vicinity of the structure;
g) the loads at the time of construction;
h) temperature variations both inside and outside the reservoir, taking into account climatic extremes
and seasonal or operational variations in the temperature of the stored water;
i) the thermal gradient between parts of the structure exposed to differing climatic conditions.
Variable actions not specified b
...