C z e c h  M e t r o l o g i c a l  I n s t i t u t e  
Okružní 31, 638 00  
Brno  
 
 
1. ------IND- 2014 0037 CZ - EN- ------ 20140203 --- --- PROJET 
Executive  summary for the EC (not part of this legislation)  
 
Instruments for measuring water flow quantity – water meters which are intended for use in 
residential and commercial zones and in light industry  are placed on the market and introduced into 
service in accordance with Directive 2004/22/EC (the Measuring Instruments Directive – MID).  They 
are subject to national metrological regulation – validation  (at specified intervals).  The subject  of this 
notified legislation is simply the validation  of measuring instruments which have already been put 
into service.  This legalisation does not concern placement on the market or introduction into service 
(with the exception of cases pursuant to Artic le 23 MID).  
The requirements imposed upon these measuring instruments in service are fully compatible with the 
MID and are based on EN 12261+A1 and EN 12480+A1 standards, which are harmonised standards 
for the MID.  
Some of the parameters specified here are  properties of measuring instruments in new condition and 
are only noted here because preserving said properties during service is merely the subject of a visual 
inspection or other inspection during the validation process . 
(End of executive summary.)  
 
 
 
 
As a body with material and local competence in matters concerning the establishment of metrological 
and technical requirements for the specified measuring instrument and the establishment of testing 
methods for type approval and validation  of the specifi ed measuring instrument pursuant to Section 14 
Paragraph 1 of Act No 505/1990 on metrology, as amended (hereinafter referred to as the ‘Metrology 
Act’), and pursuant to the provisions of Section 172 et seq. of Act No 500/2004, the Rules of 
Administrative P rocedure (hereinafter referred to as ‘RAP’), the Czech Metrological Institute (CMI) has 
launched ex officio an administrative proceeding pursuant to Section 46 of the RAP on 4 July 2013, and, 
on the basis of the documentation, enacts the following:  
 
 
I. 
G E N E R A L    M E A S U R E  
Number:  0111 -OOP -C035 -13 
Reference No  0313/006/13/Pos.,  
laying down metrological and technical requirements for specified measuring instruments, 
including the testing methods for the validation  of the following specified instrum ents:  
‘instruments for measuring water flow quantity – water meters which are intended for use in 
residential and commercial zones and in light industry ’ General Measure No 0111 -OOP -C035-13 
2  
This General Measure establishes the metrological and technical requirements for instruments for 
meas uring water flow quantity, specifically water meters which are intended for use in residential and 
commercial zones and in light industry ; said requirements apply during the process of validating said 
measuring instruments after they have been  placed onto the market or introduc ed into service.  These 
requirements are in accordance with the requirements of Government Order No 464/2005, establishing 
technical requirements for measuring instruments1, as amended (hereinafter the ‘Government Order on 
Measuring In struments’) as well as with the requirements of the harmonised standards.  
For water meters with type approval under the Metrology Act, in the amended version effective up to 
30 October 2006, i.e. prior to the implementation of Directive 2004/22/EC of the E uropean Parliament 
and of the Council, as amended, into Czech law, validation  is subject to the metrological requirements 
that were applicable when said water meters were placed into circulation.  
1   Basic definitions  
The terms and definitions pursuant to the VIM a VIML2 as well as the terms and definitions specified 
in the following shall apply for the purposes of this General Measure:  
1.1 
measuring instrument for water flow quantity, water meter   
instrument intended for the continuous measurement, recordi ng and display of the volume of water 
flowing through it under defined operating conditions  
1.2 
flow 
proportion of the actual volume of water which flowed through the water meter and the time during 
which said volume flowed through the water meter; express ed in  m3/h 
1.3 
minimum flow rate  Q1   
the minimum  flow rate  at which the water meter is required to operate within  the limits of the 
maximum permissible error  
NOTE  Minimum flow rate  was previously noted as qmin or Qmin (which is why provisions concerning Q1 also 
relate  accordingly to qmin or Qmin). 
1.4 
transitional flow rate  Q2  
flow rate  between the constant flow rate  Q3 and the minimum flow rate  Q1, and which divides the flow 
range  into two regions : the ‘lower region’ and the ‘upper region ,’ each of which  is characterised by its 
own maximum permissible error  
NOTE  The transitional flow rate  was previously noted as qt or Qt (which is why provisions concerning Q2 also 
relate  accordingly to  qt or Qt). 
                                                   
1 This Government Order implements European Parliament and Council Directive 2004/22/EC of 31 March 
2004 on Measuring Instr uments, as amended, into Czech legislation . 
2 International Vocabulary of Metrology – Basic and general concepts and associated terms (Mezinárodní 
metrologický slovník – Základní a všeobecné pojmy a přidružené termíny – VIM) and the International 
Vocabulary of Terms in Legal Metrology (Mezinárodní slo vník termínů v legální metrologii – VIML) are part of 
the technical harmonisation collection ‘Terminology in the Field of Metrology’ (Terminologie v oblasti 
metrologie) which is accessible to the public at www.unmz.cz.  General Measure No 0111 -OOP -C035-13 
3 1.5 
constant flow rate Q3  
the maximum  flow rate  at which the water meter is required to operate under the defined  operation 
conditions by a suitable means within the limits of the maximum permissible error  
NOTE  The constant flow rate  was previously noted as qp or Qp, or also qn (which is why provisions concerning 
Q3 also relate accordingly to qp, Qp or qn). 
1.6 
overl oad flow rate  Q4   
the maximum flow rate  at which the water meter is required to operate for a short period of time 
within the limits of its maximum permissible error while retaining its metrological  function, and 
consequently operating within the limits o f the maximum permissible error  
NOTE  The overload flow was previously noted as qs or Qs (which is why provisions concerning Q4 also relate 
accordingly to qs or Qs). 
1.7 
test flow   
average flow during a test, calculated based on an indication from a calibrated reference device; 
proportion  of the actual volume of water which flowed through the water meter and the time during 
which said volume flowed through the water meter  
1.8 
nominal diameter  (DN)   
alphanumeric designation for the size of the part of pipe systems which is used for referenc e purposes; 
it consists of the letter s DN followed by a whole number, which is indirectly related to the size of the 
aperture or outside diameter of the end connections in mm  
1.9 
statistical selection test   
test in which the decision whether or not the bas ic set meets the requirements based on the selection 
test  
1.10 
basic set   
set of water meters from which the selection is made and which the results of the statistical selection 
test are measured by  
1.11 
selection  
set of water meters which are selected f rom the basic set and submitted for testing for the decision on 
the basic set  
2   Metrological requirements  
The metrological requirements for water meters intended to be used in residential and commercial 
zones and in light industry are based on the requir ements of the Government Regulation on Measuring 
Instruments and use the relevant requirements from  the harmonised standards.  
The same metrological requirements which were decisive in the placement of the water meter on the 
market are to be applied when va lidating said meters.  
2.1   Rated operating conditions  
A water meter’s defined operating conditions are specified by the manufacturer.  
Range  of the defined operating conditions:  General Measure No 0111 -OOP -C035-13 
4 a) the water temperature range must meet at least the following conditions:   
from  0.1 °C to 30 °C for water meters for cold water, or  
from 30 °C to 90 °C for water meters for cold water, or  
it may operate within both ranges.  
b) the relative operating pressure range is from 0.3 bar to at least 10 bar.  
c) a nominal value for the alternating cu rrent voltage source must be defined for the power 
source, or limit values must be defined for direct current voltage.  
2.2   Measurement range  
The values for the water flow rate  range must meet the following conditions:  
Q3/Q1 
 10 
Q2/Q1 = 1.6 
Q4/Q3 = 1.25 
2.3   Maximum permissible error  
2.3.1     Maximum permitted error in lower flow rate  region  
The maximum permissible error for the volume delivered at a flow rate between the minimum flow rate  
Q1 (inclusive) and the transitional flow rate  Q2 (exclusive ), pos itive or negative, is 5 % for water of any 
temperature.  
2.3.2     Maximum permitted error in upper flow rate  region  
The maximum permissible error for the volume delivered at a flow rate between the transitional flow 
rate Q2 (inclusive) and the transitional flow rate  Q4 (exclusive ), positive or negative, is:  
2 % for water with a temperature of 
  30 °C, 
3 % for water with a temperature of 
  30 °C, 
2.3.3    Maximum permissible error during use  
When validating measuring instruments during use  in accordance with S ection 11 Paragraph 4 of the 
Metrology Act at the request of a party whose interests may be significantly compromised by 
improper measur ing, then twice  the maximum permissible error specified in Article s 2.3.1 and 2.3.2.  
shall be applied as the maximum per missible error .  
2.3.4    Assessing measuring instrument error during validation  
It must be impossible to misuse the maximum permissible error or abuse it to the systematic 
disadvantage of one party when validating a water meter.  
If all errors within the me asuring instrument’s measurement range have the same sign during this 
validation , then at least one of the errors must be less than half of the maximum permissible error.  
2.4   Measuring instrument classification   
2.4.1    Measuring instrument pressure clas ses 
The minimum allowable pressure (mAP) must be 30 kPa (0.3 bar).  
Measuring instruments are classified by the maximum allowable pressure (MAP) conforming to the 
values of the ISO series selected by the manufacturer.  The water meter must be capable of 
withstanding the internal pressure according to the applicable pressure class and must be tested using 
the applicable test.  General Measure No 0111 -OOP -C035-13 
5 2.4.2    Measuring instrument temperature class  
The measuring instruments are classified by the water temperature class conforming to the  various 
ranges selected by the manufacturer.  
2.5   Other significant metrological characteristics   
2.5.1    Flow is absent  
If the flow is absent, the indication of volume may not be changed.  
2.5.2    Reverse flow  
In the case of measuring instruments designe d to measure reverse flow, the constant flow rate  and 
measurement range may be different in each direction.  
The manufacturer must specify whether the measuring instrument is designed to measure reverse flow.  
If it is, the reverse flow volume must be either  deducted from the indicated volume, or it must be 
recorded separately.  The maximum permissible error pursuant to Articles 2.3.1 and 2.3.2 must be 
complied with for both the forward and reverse flow.  
3   Technical requirements  
The metrological requirement s for water meters intended to be used in residential and commercial 
zones and in light industry are based on the requirements of the Government Regulation on Measuring 
Instruments and use the relevant requirements from  the harmonised standards . 
During validation , measuring instruments are subject to the technical requirements which were 
decisive for said instruments’ placement on the market.  
3.1    Measuring instrument size and overall dimensions  
The size of a water meter is characterised by its nominal di ameter (DN).  Minimum threading 
dimensions are defined for measuring instruments with a threaded end connection.  
3.2   Display device  
A water meter’s display devise must be easy to read and ensure a clear and reliable visual indication of 
the flow volume.  
The indication device may contain elements for other testing methods, such as elements for automatic 
testing.   
The water volume must be indicated in cubic metres.  The m3 sign must be specified on the meter dial 
or immediately next to the numeric display.  
Every display device must be equipped with a validation  device for clear visual testing when 
validating the control element.  
The graduation of validation  may not exceed 0.5 % of the volume corresponding to the flow volume 
for 1 hour and 30 minutes at minimum  flow rate  Q1. 
3.3   Electronic device counter  
The counter may be equipped with  interfaces which allow additional devices to be connected.  If such 
an interface is used, the water meter’s hardware and software must continue to function properly and it 
must be impossible to influence the water meter’s metrological properties.  General Measure No 0111 -OOP -C035-13 
6 3.4   Auxiliary devices   
A water meter may contain auxiliary devices in addition to display devices.  The addition of such 
devices, be it temporary or permanent, may not change the measur ing instrument’s metrological 
properties.  
An auxiliary device may be used to detect a flow sensor’s activity before it is displayed on the display 
device.  
3.5   Software  
Software which is essential for the metrological properties of electronic devices must  be identifiable 
and secured.  It must be possible to identify the software by simple means.  
3.6   Power supply  
The means of connecting water meters with electronic devices is determined by the manufacturer.   
Water meters with a n electronic display device m ust be designed so that , should the external pow er 
supply fail (AC or DC) , the volume display is not lost by the measuring instrument immediately prior 
to the failure and that the display remains accessible for at least one hour.  Data must be saved to 
memo ry at least either once per day or after e ach volume equivalent to 10 minutes of flow at Q3. 
3.7   Materials and design  
The water meter’s materials may not be adversely affected by changes in water temperature within the 
operating temperature limits, i.e. the materials must be resistant to internal and external corrosion, or 
the materials must be protected by a suitable surface treatment.  
The water meter’s display device must be protected by a transparent inspection window and a suitable 
type of cover may b e used to provide additional protection.  The water meter must include a device for 
eliminating the effects of condensation at places where the risk of condensation arises on the inside of 
the water meter’s display device.  
3.8   Measuring instrument securit y and fraud prevention  
3.8.1    Mechanical protective devices  
Water meters must include protective devices which must be sealed by such means that there is no 
way to dismantle or alter the measuring instrument without  damaging the seal or protective device s 
once the water meter has been sealed both before and after the water meter has been properly installed.  
3.8.2    Electronic sealing device  
If access to the means of modifying parameters which affect the measurement results is not protected 
by mechanical m eans, access must be protected by means of a code, password, or similar, and at least 
the most recent parameter modification must be saved to memory. With replaceable parts and non-
replaceable  detachable parts, the insertion of any parts which could affect  the measurement results 
must be restricted.  
3.9   Earthing induction water meters  
The induction water meter’s electrodes and the liquid being measured must be electrically connected 
and grounded to ensure accurate measuring and prevent galvanic corrosion.  The manufacturer’s 
individual installation instructions for the specific measuring instrument design  must be followed, 
although it is generally water which is earthed by this means.  
3.10   Test water conductivity  
The conductivity of the test water for te sting induction water meters must meet the requirements in the 
type approval certificate, or the EC type testing certificate.  General Measure No 0111 -OOP -C035-13 
7 4   Water meter markings  
A water meter must be clearly and visibly labelled with the information pursuant to Article 4.1 by such 
means that:   
a) all information is listed together on a single label,  
b) or the information is arranged on the housing, dial of the display device, identification label or 
cover of the measuring instrument, provided that the cover is not removable.  
4.1  Markings on the measuring instrument  
A water meter must be clearly and visibly labelled with information which is important for validation : 
– measuring unit:  cubic metre,  
– numeric value Q3, 
– the Q3/Q1 ratio  (preceded with ‘ R’), 
– the Q3/Q1, if it differs from 1,6,  
– the m aximum allowable pressure, if it differs from 1 MPa (10 bar),  
– flow direction (depicted on both sides of the body – or only on one side – with an arrow 
indicating the flow direction so as to be  easily visible under any circumstance),  
– the letter V or H, if the measuring instrument is only able to operate in a vertical or horizontal 
position,  
– the temperature class, if it differs from T30,  
– pressure loss class, if it differs from 
 P 63, 
– class of sensitivity to irregularity in the velocity field,  
– the manufacture r’s name or brand,  
– year of manufacture (last 2 digits) and serial number (which should be as close as possible to the 
display device),  
– the type approval mark according to EU legislation,  
– demand factor level of the climatic and mechanical environment,  
– EMC c lass, 
– output signals for auxiliary devices (type/level), if any,  
– requirements for external power source:  voltage – frequency,  
In cases in which the electrical power source is a battery:  
– in the case of a replaceable battery, the latest date upon which the battery must be changed 
must be marked on the measuring instrument,  
– in the case of a fixed internal battery, the latest date upon which the measuring instrument 
must be replaced must be marked on the measuring instrument,  
The water meter must also be marke d with a mark indicating how it was placed on the market:    
– type approval mark pursuant to Act No 505/1990 on metrology, as amended, or EEC type 
testing certificate mark pursuant to this Government Regulation,  
– ‘CE’ mark of conformity, in the case of water meters approved prior to this Government 
Regulation’s entry into legal effect,  
– ‘CE’ mark of conformity and supplementary metrological mark in the case of water meters 
approved in accordance with this Government Regulation.  General Measure No 0111 -OOP -C035-13 
8 4.2   Placement of the official s eal 
The placement of official seals  is defined  by the type approval certificate, EC type testing certificate or 
other document applied during the conformity assessment when the instrument was placed on the 
market and introduced into service.   
5   Type appr oval of measuring instruments  
Water meters which are intended for use in residential and commercial zones and light industry are 
placed on the market and introduced into service in accordance with the Government Regulation on 
Measuring Instruments1) and ar e thus not subject to type approval.  
6   Initial validation  
Water meters which are intended for use in residential and commercial zones and light industry are 
placed on the market and introduced into service in accordance with the conformity assessment 
pursuant to the Government Regulation on Measuring Instruments.   
Initial validation  applies only to measuring instruments which, at the given time, have a valid type 
approval certificate with the application of transitional provisions pursuant to Section 9 of  the 
Government Order on Measuring Instruments, and to the validation  of measuring instruments 
following repairs.  
A procedure identical to the follow -up validation pursuant to Chapter 7 is applied during the initial 
validation.  
7   Subsequent validation  
Follow-up validation (i.e. each validation of a measuring instrument conducted after the previous 
validation) and validation pursuant to Section 11 Paragraph 4 of the Metrology Act (if applicable) is to 
be conducted in accordance with this General Measure, r egardless of whether said measuring 
instrument was placed on the market and into circulation in accordance with the Metrology Act or in 
accordance with the Government Regulation on Measuring Instruments.  
During validation, measuring instruments are subject  to the technical requirements which were 
decisive for said instruments’ placement on the market.  
7.1   Overview of tests conducted  
The following tests and activities are to be conducted during each validation:  
a) visual inspection,  
b) function tests:  
– test using  static pressure , 
– accuracy test.  
7.2   Visual inspection  
This visual inspection of the water meter assesses whether:  
– the measuring instrument submitted for validation conforms to the approved type or to the 
design with which conformity was declared during placement on the market, and attention 
must be paid to checking labelling pursuant to Chapter 4,  
– the measuring instrument is mechanically damaged and metallic parts exhibit traces of 
corrosion,  General Measure No 0111 -OOP -C035-13 
9 – the measuring instrument’s display of volume was not lost prio r to a power cut at the location 
of use and whether the display remained accessible in accordance with Article 3.6 (in the case 
of water meters with an electronic display device),  
– the supply batteries are in proper condition.  
If the measuring instrument do es not meet the visual inspection requirements, no further tests need be 
performed.  
7.3   Function tests   
7.3.1    Testing device  
The expanded measurement uncertainty of the actual volume indicated by the testing device may not 
exceed 1/3 of the water meter ’s maximum permissible error.  
The ‘collection method’ is used to determine the water meter’s measurement error. With this method, 
the quantity of water flowing through the water meter is collected in one or more collection tanks, and 
its quantity is determ ined by volume or weighing.  The measurement error is the difference of the 
measured volume value indicated by the test water meter minus the indication of the calibrated testing 
device under reference conditions.  
The defined minimum volume which must flow through the water meter during the test depends on the 
requirements established by testing the effects of start -up an d shutdown (time error), as well as on the 
type and design of the display device (value of the validation graduation scale).  
Measuring inst ruments are tested either individually or in groups.  In the latter case, the individual 
properties of the measuring instrument must be precisely defined.  Measuring instruments and testing 
devices must be prevented from reciprocally influencing one another.  If measuring instruments are 
tested in series, the pressure at the output of each measuring instrument must be sufficient to prevent 
cavitation.  
7.3.2    Test using static pressure  
A test whose results are capable of demonstrating leak-tightness must be co nducted using pressure 
equivalent to at least 1.6 MAP for a period of one minute.  
7.3.3    Accuracy test  
Water meters’ measurement error must be determined for at least the following three flow rates : 
between Q1 and  1.1Q1, 
between Q2 and 1.1 Q2, 
between 0.9 Q3 and Q3, 
Additional flow rates  may be specified on the type approval certificate or conformity assessment 
certificate.  
The temperature of the test water over the course of measuring instrument validation must be as 
follows, depending on temperature class:  
T30, T50:   any temperature between 0.1 °C and 30 °C  
T70 and T180:   any temperature between 0.1 °C and 30 °C  and (50 ± 5) °C  
T30/70 and T30/180:   (50 ± 5) °C  
Errors determined at any of the above -mentioned flow rates  may not exceed the maximum permissible 
error specified in Articles 2.3.1 and 2.3.2 under the conditions of Article 2.3.4.  General Measure No 0111 -OOP -C035-13 
10 7.4   Follow -up validation of volumetric water meters for cold water using statistical selection 
tests  
7.4   For follow -up validations of volumetric water meters for cold w ater installed on a water supply 
network, a statistical selection test of the specified basic set of water meters may be used upon request 
in the case of volumetric water meters for cold water.  
7.4   Basic set for statistical selection test  
A statistical s et may consist of only volumetric water meters for cold water from a single 
manufacturer, of the same type, nominal diameter DN, connection method, size of the constant flow 
rate Q3 and ratio R of flow rate  Q3/Q1 (or metrological classes).   
A basic set of water meters must be defined by the same operating conditions on the water supply 
network.  Only water meters installed in an area with the same water source may be in a single basic set.  
This area must be confirmed by a written declaration from the water s upplier (water supply company).  
Only volumetric water meters for cold water which have undergone suitable validation or a conformity 
assessment when introduced into service in the same calendar year may be included in the basic set.  
7.4.2    Statistical met hod used  
A statistical selection test can be conducted by means of one or two selections from the basic set of 
volumetric water meters for cold water in accordance with recognised statistical methods.  The 
selection conducted may contain a specified set of reserve  volumetric water meter s for supplementing 
the test selection over the course of the tests.  
Logistical and other details on the performance of the statistical selection test, including inspection  
plans, are established by the metrological institute conducting the validation according to its internal 
rules.  
7.4.3    Visual inspection   
All volumetric water meters submitted for selection must undergo the visual inspection pursuant to 
Article 7.2.  If a volumetric water meter from the selection does not pa ss the visual inspection, it can be 
replaced by a volumetric water meter from the set of reserve volumetric water meters until the set of 
reserve volumetric water meters is exhausted.  
7.4.4    Accuracy test   
All volumetric water meters submitted for selecti on must undergo an accuracy test.  The accuracy test 
must be conducted at three test flow rates :  
– minimum flow rate  Q1,  
– transitional flow rate  Q2,  
– constant flow rate  Q3.  
During the accuracy test, three measurements must be conducted at each test flow rat e. If a severe 
error, i.e. an error exceeding 15 % (for Q2 and Q3) or 24 % (for Q1), appears during any of the 
measurements, then a fourth measurement which will replace that measurement must be conducted 
immediately , after which the measurement cannot be repeated again for the flow rate  in question (the 
maximum test programme in this case is four tests at Q1, four tests at Q2, and four tests at Q3).  
The test is declared to be suitable if at least two of three results and the arithmetic average of the 
results of three tests at the given flow rate  are within the limits of the maximum permissible erro rs 
specified in Articles 2.3.1 and 2.3.2.  General Measure No 0111 -OOP -C035-13 
11 7.4.4    Evaluation of the results of the statistical selection test  
7.4.4.1    A controlled selection of volumetric wate r meters is evaluated as being suitable if the 
requirements for acceptance were met according to a previously accepted inspection plan for the 
selection check.  Otherwise, the result will be deemed unsatisfactory.  
7.4.4.2    If the selection check ends in an  unsatisfactory result, all volumetric water meters in the basic 
set will be deemed unsatisfactory.  The entire unsuitable basic set of water meters evaluated , including 
any part thereof, may no longer be validated via statistical selection test.  All water meters of the basic 
set which have not been dismantled may be used for the term of validity of their original validity, after 
which each must undergo a follow -up validation.   
7.5   Testing a water meter during the term of validity of its validation at the installation location  
This test is conducted to check whether the water meter, in the function of a specified measuring 
instrument, meets the metrological and technical requirements of this General Measure, is installed 
properly and meets the requirements for measurement accuracy during service.  
7.5.1    Tests conducted  
The test of a water meter at it installation location during the term of validity of its validation consists 
of: 
– a visual inspection of the tested water meter and its installation,  
– a prelimin ary operation test,  
– leak-tightness  test, 
– accuracy test.  
7.5.2    Visual inspection  
The visual inspection of the water meter assesses whether:  
– the water meter being tested conforms with the approved type or the type for which type 
conformity was declared,  
– it is properly installed and whether it is mechanically damaged,  
– the information on the water meter is in accordance with the type approval certificate or 
document on conformity assessment,   
– is properly secured with  official seals.  
In the case of water meter s which did not pass the visual inspection, this fact must be recorded in the 
test report, including a sufficient specification of the exact form of non -conformity.  The water meter 
test is then continued.  
7.5.3    Testing equipment  
The following test equipm ent is used at the installation location when testing the water meter:  
– a technically suitable reference water meter with established metrological traceability with 
metrological parameters corresponding to those of the test water meter, and which is fitted 
with a regulation valve, or  
– a reference measurement vessel with a regulation valve for adjusting the flow rate  during the 
test; the vessel must have a validation graduation scale value of 0.01 L for volumes of up to 
and including 10 L, and 0.03 L for volum es over 10 L; the spacing between the individual 
graduations on the scale must be 4 mm,   
– a connection tube with a suitable connection for discharge from the pipe system and a vessel 
regulation valve,  General Measure No 0111 -OOP -C035-13 
12 – a thermometer with established metrological traceability  with an accuracy of ±1  °C. 
The measurement uncertainty of the test device may not exceed 1/3 of the water meter’s maximum 
permissible error.  
7.5.4    Leak -tightness inspection   
An etalon for the flow quantity of water is connected after the test water mete r to one outlet from the 
water supply pipe by means of a connection tube.  All other outlets must be closed.    
The test water meter is not manipulated, so as to retain its present status and any potential installation 
effect during the test.   
The inspectio n checks the tightness of the shut -off valve and all other valves and outlets from the 
water supply system which, if loose , may cause the measured water to leak between the test water 
meter and the etalon.  It must be ensured that all water flowing through  the test water meter also flows 
through the etalon.   
The leak -tightness of the tube connection is to be controlled visually.  
7.5.5    Preliminary operation test  
The test is conducted for a period of at least 5 minutes at the maximum attainable flow rate  from the 
water supply system.  During the test, it is ascertained whether there are any air bubbles in the water 
supply system.  
7.5.6    Accuracy test  
The accuracy test must be conducted at a minimum flow rate  of Q1 and a transitional flow rate  of Q2, 
calcu lated based on the water meter’s markings, and at the maximum attainable flow rate  from the 
water supply system, which must at least be the range of (2 
  Q2 to Q3). The test flow rates  for testing 
the accuracy of the water meter at the installation location a re as follows:  
a) minimum flow rate  Q1 of the water meter being tested, the average flow rate  value must 
remain within a range of  ( Q1 to 1.1 
  Q1) during the test,  
b) transitional flow rate  Q2 of the water meter being tested, the average flow rate  value must 
remain within a range of ( Q2 to 1.1 
  Q2) during the test,  
c) the maximum attainable flow rate , the average flow rate  value must remain within a range of 
(2 
 Q2 to Q3) during the test.  
If it is not possible to attain a flow rate  of 2 
  Q2 because the water met er is unsuitable for the specific 
installation and the water pressure at the installation location is inadequate, then this fact must be 
noted in the test report.  
If it is not possible to achieve a flow rate  of Q1, then this fact must also be noted in the test report and 
the test will not be continued.    
The water temperature during the course of testing a water meter for cold water, i.e. water with a 
temperature between (0.1 to 30) ° C, and during the course of testing a water meter for hot water, i.e. 
water with a temperature between (30 to 90) °C , is to be measured using a thermometer with an 
accuracy of ±1  °C.  
The defined minimum volume of water which must flow through the water meter during the test 
depends on the requirements established by testing the  effects of start -up and shutdown (time error), as 
well as on the type and design of the water meter’s display device .  
During the accuracy test, at least one measurement must be conducted at each test flow rate . The test is 
declared to be suitable if the measurement result is within the limits of the maximum permissible 
errors specified in Article 2.3.3.  
The accuracy test may by conducted using the collection or volume method.  General Measure No 0111 -OOP -C035-13 
13 7.5.6.1    Collection method  
With an accuracy test conducted using the collection  method, the quantity of water flowing through 
the water meter is collected in a measurement vessel and its quantity is determined on the 
measurement vessel’s scale.   
The measurement error is determined by comparing the volume indicated by the water meter being 
tested with the quantity of water which flowed indicated on the measurement vessel.   
The flow rate  Q1, Q2 and maximum attainable flow rate  from the water supply system pursuant to 
Article 7.5.6 Points a) through c) is adjusted by constricting the reg ulation valve at the input to the 
measurement vessel.  
7.5.6.2    Volume method  
With an accuracy test conducted using the volume method, the volume which flowed through the 
water meter being tested is compared with the volume which flowed through the etalon for the 
quantity of water which flowed using an induction flow gauge (for instance).  The induction flow 
gauge must be calibrated, including its stilling sections (at a length of at least 10 D before the 
measuring instrument and at least 5 D after the measuri ng instrument), with a maximum permissible 
error of 0.6 %.  Calibration uncertainty may not exceed ±0.2 %.   
The water pressure at the output from the etalon must be adjusted using an outlet tube.  The pressure 
after the etalon must be at least 5 kPa (0.05 ba r), even at a flow rate of zero (corresponding to 0.5 m of 
the water column).   
The flow rate  Q1, Q2 and maximum attainable flow rate  from the pipe system pursuant to Article 7.5.6 
Points a) through c) is adjusted by constricting one of the regulation valve s at the output after the 
etalon with the stilling sections.   
7.5.6.3    Evaluation of the results of the accuracy test at the installation location  
If the water meter fails to pass the external inspection or accuracy test, it  is deemed not to meet the 
defined requirements.  
8   Notified standards  
For the purposes of specifying the metrological and technical requirements for measuring instruments 
and for the purposes of specifying the testing methods for validation based on this General Measure, 
the CMI shall  provide notification of the Czech technical standards, other technical standards or 
technical documents of international or foreign organisations, or other technical documents containing 
more detailed technical requirements (hereinafter referred to as ‘no tified standards’).  The CMI 
announces a list of these notified standards assigned to the applicable measure together with the 
General Measure by means accessible to the public (at the internet site www.cmi.cz).  
Notified standards or parts thereof shall be deemed as complied with, within the scope of and under 
the conditions laid down by this General Measure, if the requirements laid down by this measure, to 
which these standards or parts thereof apply, are complied with.  
 General Measure No 0111 -OOP -C035-13 
14 II. 
G R O U N D S   
The CMI issues t his General Measure laying down metrological and technical requirements for 
specified measuring instruments and the testing methods for the validation of these specified 
measuring instruments in order to implement Section 24c of the Metrology Act.  
Regulati on No 345/2002 establishing measuring instruments for compulsory validation and measuring 
instruments subject to type approval, as amended, classifies instruments for measuring the flow 
quantity of water – measuring instruments for cold and hot water as m easuring instruments subject to 
validation under Item 1.3.9 a), b) in the Annex to the Second List of Specified Measuring instruments.  
The CMI hereby issues this General Measure establishing metrological and technical requirements for 
instruments for measu ring the flow quantity of water – water meters intended for use in residential and 
commercial zones and light industry’ and the testing methods for validating these specified measuring 
instrument for the purpose of implementing Section 24c of the Act on Me trology for this specific type 
of measuring instrument: ‘instruments for measuring the flow quantity of water – water meters 
intended for use in residential and commercial zones and light industry.’  
This legislation (General Measure) was notified in accord ance with European Parliament and Council 
Directive 98/34/EC of 22 June 1998 on the procedure for the provision of information in the field of 
technical standards and regulations and rules on Information Society services, as amended.  
 
 
III. 
LEGAL INSTRUCTI ONS   
Legal remedies pursuant to Section 173(2) of the Rules of Administrative Procedure may not be filed 
for General Measures.  
In accordance with the provisions of Section 172(5) of the Rules of Administrative Procedure , 
decisions on objections may not be revoked and appeals may not be made against them.  
The General Measure’s conformity with the statutory regulations can be evaluated in the research 
procedure pursuant to the provisions of Section 94 to 96 of the Rules of Administrative Procedure.  The 
party involved may submit a motion to conduct a research procedure to the administrative body which 
issued this General Measure.  If the administrative authority finds no reasons to commence the review 
proceedings, it shall communicate and provide grounds for this fact within thirty days.  Rulings on the 
initiation of a research procedure may be issued within three years as of the Gen eral Measure’s entry into 
legal effect in accordance with the provisions of Section 174 Paragraph 2 of the Rules of Administrative 
Procedure.  
 
 
IV. 
ENTRY INTO LEGAL EFF ECT  
This General Measure shall enter into legal effect on the fifteenth day following th e date of its 
promulgation (Section 24d of the Metrology Act).  
 
 
 General Measure No 0111 -OOP -C035-13 
15 ...…………………………..............  
RNDr.  Pavel Klenovský  
Director General