WORKING DRAFT OF 2nd March  2022 
  
1 
 STATUTORY INSTRUMENTS  
2022 NO……  
THE WEIGHTS AND MEASURES (WATER METERS) RULES, 202 2 
(Under sections 19(4), 22(a) and 43 of the Weig hts and Measures Act, Cap. 103)  
 
IN EXERCISE of the powers conferred on the Minister responsible for trade by sections 43, 22 
and 33 of the Weights and Measures Act, Cap. 103 these Rules  are made this …. day of ….  2022 
 
PART I  - PRELIMINARY  
1 Title  
These Rules  may be cited as The Weights and Measures (Water Meters) Rules , 202 2. 
2 Commencement  
These Rules  shall come into force on the ……… ……… … 2022. 
3 Interpretation  
In these Rules , unless the context otherwise requires -  
“Act” means the Weights and Measures Act, Cap. 103;  
“Actual volume” means total volume of water passing through the meter as determined by a 
suitable measurement standard, disregarding the time taken;  
“Ancillary devices” means a device intended to perform functions, directly involved in 
elaborating, transmitting or  displaying measurement results;   
“Certificate of verification” means a document issued by an Inspector to certify that a water 
meter conforms to the prescribed requirements of these Rules;  
“Combination meter” means a meter comprising one large meter, one small meter, and a 
changeover device that, depending on the magnitude of the flow rate passing through the 
meter, automatically directs the flow through either the small or the large meter, or both;  
“Concentric meter” means a type of meter that is fitted i nto a closed conduit by means of a 
manifold;  
“Contractor” means person that installs water meters and the distribution  grid, and includes 
the Ministry of Water and Environment.   
“Control element” means an element which, in an indicating device comprisin g several 
elements, carries the graduated scale with the verification scale interval ; WORKING DRAFT OF 2nd March  2022 
  
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 “Correction devices” means devices used to compensate for systematic errors in a 
measurement;  
“Customer” means a person  that pays for water consumption.   
“Error of indication” means the difference between indicated volume and actual volume;  
“Indicated volume” means volume of water indicated by the meter under test, corresponding 
to the actual volume;  
“Initial verification” means a series of tests and visual examinati ons carried out to determine 
whether a water meter manufactured to replicate a given pattern conforms to that pattern and 
to these Rules, and that its metrological characteristics lie within the limits required for initial 
verification of copies of that pa ttern;  
“Manifold” means pipe fitting specific to the connection of a concentric meter;  
“Maximum permissible error” means extreme value of relative error of indication with 
respect to a known reference quantity value, prescribed by these Rules for a given m eter; 
“Metrology” means science of measurements;  
“Minister” means the minister responsible for trade ; 
“New meter” means a water meter imported or manufactured locally after the commencement 
of these Rules;  
“Old meter” means  a water meter in service or stocked in Uganda before commencement of 
these Rules;  
“pattern/type approval” means the recognition that the pattern of the water meter conforms 
to relevant statutory requirements and relates to the class produced by the manufacturer and 
results in the iss uance of the pattern approval certificate ;  
“Person” includes a company, association, body of persons corporate or unincorporated;  
“Potable water” means water that is suitable for human consumption;  
“Primary indication” means indication which is subject to  legal metrological control;  
“Relative error of indication” means the ratio of error of indication to the actual volume and 
is expressed as a percentage;  
“Subsequent verification” of a water meter means mandatory periodic verification, 
verification after repair, and voluntary verification. It may be carried out before expiry of the 
period of validity of a previous verification either at the request of the user (owner) or when 
its verification is declared to be no longer valid;  WORKING DRAFT OF 2nd March  2022 
  
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 “Supplier” has the same meani ng as seller in the Act and includes importers and local  
manufacturers  of water meters;  
“Verification scale interval” means the lowest value scale division of the control element of 
an indicating device;  
“Water meter" means a measuring instrument intended to measure continuously, memorize 
and display the volume of water passing through the measurement transducer at metering 
conditions;  
“Water utility” means an entity such as water authority, community organization, local 
government, service provider and ind ividual person authorized to distribute water in a 
demarcated area in Uganda.  
 
PART II – SCOPE  
4 These Rules  shall apply to  water meters ;  
a) for use for trade  of cold potable wate r and hot water .  
b) used for purposes of production, irrigation , and natural resource monitoring.  
c) whose principles of operation include among others mechanical, electromagnetic 
and ultrasonic . 
 
5 These Rules  shall also apply to ancillary devices . 
 
PART III – RES PONSIBILITIES OF KEY STAKEHOLDERS  
Customer  
6 A customer shall grant to an Inspector for purposes of inspection and verification access to a 
water meter in their premises.  
Supplier  
7 A supplier shall:  
a) apply to the Minister for a certificate  of approval for a pattern of water meters they 
intend to supply . 
b) supply only water meters whose pattern has been approved and bear a valid stamp of 
verification.  
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 Water Utility  
8 A water utility shall : 
a) comply with the manufacturer's conditions concerning the use and permitted 
operating conditions where such affect  metrological performance of the meter.  
b) install only water meters whose pattern has been approved and bear a valid stamp of 
verification.  
c) ensure that a water meter for s ettlement of water consumption bears a valid stamp of 
verification.  
 
Contractor  
9 A contractor shall:  
a) comply with the manufacturer's conditions concerning  installation where such affect 
metrological performance of the meter.  
b) install only water meters whose pattern has been approved and bear a valid stamp of 
verification.  
 
PART I V – PAT TERN APPROVAL OF WATER METERS  
10 A water meter shall be of a pattern  in respect of which a certificate of approval has been 
granted by the Minister as provided for by section 19  (1) of the Act. 
 
11 During pattern approval, the inspector shall determine whether the water meter type  meets 
the metrological requirements prescribed in part VI  and the technical requirements prescribed 
in part VII of these Rules.  
 
12 The number of samples submitted for pattern approval of a water meter shall be as specified 
in Table 1 of schedule 1. 
 
13 For type approval of a water meter with electronic devices, five samples shall be supplied, 
which may be different samples from those supplied for other testing, with at least one meter 
being subjected to all the appropriate tests.  
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 PART V  – VERIFICATION AND INSPECTION OF WATER METERS  
14 After pattern approval  and prior to its initial use , a new water meter shall be subjected to 
initial verification . 
 
15 Old meters in stock shall also be subjected to initial verification.  
 
16 Old meters in service shall be subjected to subsequent verification and inspection.  
 
17 For verification and inspection of water meters, grouping into inspection lots shall be 
according but not limited to the year of manufacture, year of installation, serial number , 
batches , customer number or geographical region.  
 
18 Sampling plans prescribed in Tables 2 and 3 of schedule 2 shall be used for verification and 
inspection of water meters for a group having at least nine meters.  
 
19 During verification and Inspection, the inspector shall determine whether the water meter 
meets the metrological requirements prescribed in part VI  and the technical requirements 
prescribed in part VII  of these Rules.   
 
20 A certificate of verification shall be issued  for a water meter that an Inspector has passed as 
fit for trade use.  
 
21 A stamp of verification on a water meter shall remain in force for a period of three years or 
1,000,000 litres of use  from the date of stamping , whichever comes first . 
 
22 A water meter  which do es not meet the technical and metrological requirements of these 
Rules  shall be reject ed as un fit for use for trade  and withdrawn from service  where applicable . 
 
23 A repaired/adjusted water meter  shall be re -verified prior to  its use or re-use. 
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 PART V I – METROLOGICAL REQUIREMENTS FOR WATER METERS  
Meter temperature classes  
24 The meters shall fall under water temperature classes corresponding to the various ranges, 
from the values given in Table 4 prescribed in schedule 3. 
 
Water meters with  reverse flow  
25 For a water meter not designed to measure reverse flow, the meter shall prevent reverse flow  
by means of in -built non -return valves . 
 
26 For a water meter designed to measure reverse flow, the volume passed during reverse flow 
shall be either subtracted from the indicated volume or recorded separately.  
 
Accuracy class and maximum permissible error  
27 A water meter shall be designated as eithe r accuracy class 1 or accuracy class 2, as specified 
by the ma nufacturer.  
 
28 The maximum permissible error for the relative error of indication  under rated operating 
conditions for a water meter shall be as specified in Table 5 of schedule 3. 
 
PART VII – TECHNICAL REQUIREMENTS FOR WATER METERS  
Marks and inscriptions  
29 A water meter shall be clearly and indelibly marked with the information in schedule 4 either 
grouped or distributed  on; 
a) the casing,  
b) the indicating device dial,  
c) an identification plate or  
d) the meter cover, if it is not detachable.  
 
30 For a combination meter, the markings in schedule 4 shall refer to the combination meter 
considered as a single meter.  
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 31 These markings shall be visible without dismantling the water meter after the instrument has  
been placed on the market or put into service.  
 
32 A water meter shall have a place provided for af fixing the verification mark(s),  which shall 
be visible without dismantling the meter after it has been placed on the market or put into 
service.  
 
Materials for water meters  
33 A water meter shall be manufactured from materials which;  
a) are of adequate strength and durability.  
b) cannot be adversely affected by th e water temperature variations , within the working 
temperature range  as specified in table 6 of schedule 5 . 
c) are non -toxic, non -contaminating, biologically inert, and resistant to internal and 
external corrosion.  
 
Construction of water meters  
34 A water meter shall be of such design and construction that it does not facilitate the 
perpetration  of fraud.  
 
35 A water meter indicating device shall be protected by a transparent window whose design 
will prevent condensation from forming on its underside.  
 
36 A water meter shall be fitted with a metrologically controlled display which is readily 
accessible to the customer, wi thout requiring the use of a tool.  
 
37 A strainer or filter shall be fitted at the inlet of a water meter.  
 
 
 
 
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 Indicating device  
(1) Function and indicating range  
38 The indicating device of the water meter shall provide an easily read, reliable and 
unambiguous  visual indication of the indicated volume.  
 
39 For a combination meter, the sum of the two readings from the indicating devices shall 
provide the indicated volume.  
 
40 The indicating device shall be able to record the indicated volume  for a water meter flow 
range as provided for in Table 7 of schedule 5. 
 
41 The indicating device shall not pass through  zero until it has reached the  maximum value 
shown in Table 7 of schedule 5 when it resets.  
 
(2) Unit of measurement, symbol, and its placement  
42 The indicated volume of water shall be expressed in cubic metres.  
 
43 The symbol 𝑚3 shall appear on the dial or immediately adjacent to the numbered display.  
 
(3) Color coding for indicating devices  
44 The color s applied either to pointers, indexes, numbers, w heels, discs, dials or to the aperture 
frames  shall be ;  
a) Black  to indicate the cubic metre and its multiples.  
b) Red to indicate sub -multiples of a cubic metre.  
 
45 Other means of indicating the cubic metre, its multiples and its sub -multiples may be used 
for a  water meter provided there is no ambiguity in distinguishing between the primary 
indication and other displays.  
 
 
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 Adjustment and correction  
46 A water meter shall have an adjustment device which will be used for adjusting errors of 
indication.  
 
47 For a water meter fitted with correction devices, the corrected volume at metering conditions 
shall meet the  accuracy  requirements specified under  Rule 2 8 and table 5 in schedule 3  
 
48 Correction devices shall not be used for adjusting errors of indication.  
Protection de vices  
(1) General  
49 A water meter shall include protection devices which can be sealed so as to prevent 
dismantling or modification of the meter, its indicating device, its adjustment device or its 
correction device, without damaging these devices.  
 
50 The protection shall  limit access to parameters that influence the determination of the results 
of measurements either by mechanical or electronic sealing devices . 
 
(2) Electronic sealing devices  
51 Access  to parameters described in Rule 49 shall only be allowed to an Inspector of Weights 
and Measures, for example by means of a code (password) or of a special device (such as a 
hard key).  
 
52 The code  described in Rule 5 1 shall be capable of being changed.  
 
53 It shall  be possible for evidence of  intervention  including the date and a characteristic element 
identifying the Inspector of Weights and Measures making the intervention  to be available 
for a period of time of three years.  
 
54 If deletion of a previous intervention is necessary to permit a new record, the oldest record 
shall be deleted.  
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 (3) Meters with parts which can be disconnected  
55 For meters with parts which may be disconnected one from another by the user and which 
are interchangeable, the following provisions shall be fulfilled:  
a) It sha ll not be possible to access parameters that participate in the determination of results 
of measurements through disconnected points u nless the provisions in Rules 49 and 5 0 
are fulfilled.  
 
b) Interposing any device which may influence the accuracy shall be prevented by means of 
electronic and data -processing securities or, if this is not possible, by mechanical means.  
 
56 For meters with parts which may be disconnected one from another by the user and which 
are not interchangeable, the provisions of Rule s 49 and 50 shall apply.  
 
a) Moreover, these meters shall be provided with devices or means which do not allow them 
to operate if the various parts are not connected according to the approved type.  
 
b) They shall be provided with a device that prevents any measuremen t after any 
unauthorized disconnection and subsequent reconnection by the user.  
 
Pressure loss  
57 The pressure loss through a water meter, including its filter or strainer shall not be greater 
than the maximum pressure loss as specified by the manufacturer in  accordance with table  8 
in schedule 6. 
 
58 For a concentric meter, the pressure loss across the meter and its respective manifold shall 
meet the requirements of table 8 in schedule 6. 
 
 
 
 
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 Installation conditions  
59 The water meter shall be installed such that  it is completely filled with water under normal 
conditions.  
 
60 If the accuracy of a meter is affected by disturbances in the upstream or downstream pipeline, 
the water meter shall be provided with a sufficient number of straight pipe lengths, with or 
withou t a flow straightener, as specified by the manufacturer in accordance wit h tables 9 and 
10 in schedule 6. 
 
61 A water meter shall be able to withstand the influence of disturbed velocity fields resulting 
from velocity -profile distortion or swirl.  
 
62  During the application of these flow disturbances  described in Rule 6 0, the error (of 
indication) shall meet the requirements of Rule 28. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 SCHEDULE  1 
REQUIREMENTS FOR TYPE/PATTERN APPROVAL  
(1) External examination  
Before undergoing type evaluation tests, each type of water meter submitted shall be 
examined externally to ensure that it complies with the provisions of the relevant 
preceding clauses of these Rules  
(2) Number of samples  
The evaluation tests shall be made on the minimum number of samples of each type 
shown in Table 10 below as a function of the water meter designation 𝑄3 of the type 
presented. The Inspector responsible for type evaluation may request further specimens.  
 
Table 1 – Minimum number of water meters to be tested for type approval  
Meter designation,  
Q3 (m3/h) Minimum number of meters to be  
tested for all meter types, excluding the tests  
required for meters with electronic devices  
Q3 ≤160 3 
160 < Q3 ≤ 1600  2 
1600  < Q3 1 
 
 
 
 
 
 
 
 
 
 
 
 
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 SCHEDULE 2  
Table 2 – For smaller groups, Single Sampling Plan  
 
 
No.  
 
Lot size   
 
Sample size  Number of non - conforming meters   
 
Spare meters  Criteria for 
acceptance of lot  Criteria for 
rejection of lot  
1.1 9 to 15  3 0 1 1 
1.2 16 to 25  5 0 1 1 
1.3 26 to 50  8 0 1 1 
1.4 51 to 90  13 1 2 2 
1.5 91 to 150  20 1 2 2 
 
Table 3 – For larger groups, Double Sampling Plan  
 
 
Lot size   
 
Sample   
 
Sample 
size  
 
Cumulative 
sample size  Number of non – conforming meters ∗∗  
 
Spare 
meters  Criteria for 
acceptance  Criteria for 
rejection  Criteria for 
required 2nd 
sample ∗ 
 
151 to 1200  first 32 32 0 2  
1 6 
second  32 64 1 2 6 
 
1201 to 3200  first 50 50 1 4  
2 to 3  10 
second  50 100 4 5 10 
 
3201 to 10000  first 80 80 2 5  
3 to 4  16 
second  80 160 6 7 16 
 
10001 to 35000  first 125 125 5 9  
6 to 8  25 
second  125 250 12 13 25 
 
Explanations:  
∗ A second sample of the same size as the first sample shall be randomly drawn from 
the lot if the non -conforming meters stated in this column are part of the first 
sample.  
∗ ∗ In each of the lines headed by “second sample”, the number of non -conforming 
meters relates to the cumulative sample size.  WORKING DRAFT OF 2nd March  2022 
  
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 SCHEDULE 3  
Table 4 - Meter temperature classes  
Class  mAT ( °C) MAT (°C) 
T30 0.1 30 
T50 0.1 50 
T70 0.1 70 
T90 0.1 90 
T130  0.1 130 
T180  0.1 180 
T30/70  30 70 
T30/90  30 90 
T30/130  30 130 
T30/180  30 180 
 
Table 5 – Maximum Permissible Errors for water meters  
Meter Accuracy 
Class  Flow rate zone  Temperature 
classification  Maximum Permissible 
error (%)  
 
 
 
Class 1  Upper  
(Q2 ≤ Q ≤ Q4) 0.1°C to 30°C  ±𝟏 
Above  30°C  ±𝟐 
Lower  
(Q1 ≤ Q ≤ Q2) All temperatures  ±𝟑 
 
 
Class 2  Upper  
(Q2 ≤ Q ≤ Q4) 0.1°C to 30°C  ±𝟐 
Above  30°C  ±𝟑 
Lower  
(Q1 ≤ Q ≤ Q2) All temperatures  ±𝟓 
 Q1(minimum  flow rate) is the lowest flow rate at which the water meter is to operate 
within the maximum permissible errors.  
 Q3 (permanent  flow rate) is the highest flow rate within the rated operating conditions at 
which the meter is to operate within the maximum permissible error.  
 Q2 (transitional flow rate) is the flow rate between the permanent flow rate and the 
minimum flow rate that divides the flow rate range into two zones; upper and lower flow 
rate zones.  
 Q4 (over  load flow rate) is the highest flow rate at which the meter is to operate for a 
short period of time within  the maximum permissible errors.  WORKING DRAFT OF 2nd March  2022 
  
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 SCHEDULE  4 
MARKS AND I NSCRIPTIONS  ON A WATER METER  
a) Type approval sign/mark/ number . 
b) Unit of measurement.  
c) Accuracy  class w here the accuracy class differs from class 2 .  
d) Numerical value of Q3 and the ratio  Q3
Q1: if the meter measures reverse flow and the values of Q3 
and the ratios Q3
Q1 are different in the two directions, both values of Q3 and Q3
Q1 shall be inscribed; 
the direction of flow to which each pair of values refers shall be clear. The ratio Q3
Q1 may be 
expressed as R. If the meter has different values of Q3
Q1 in horizontal and vertical positions, both 
values of Q3
Q1 shall be inscribed, and  the orientation to which each value refers shall be clear.  
e) Name or trademark of the manufacturer.  
f) Year of manufacture, the last two digits of the year , or the month and year of manufacture.  
g) Serial number (as near as possible to the indicating device).  
h) Direction of flow, by means of an arrow (shown on both sides of the body or on one side only 
provided the direction of flow arrow is easily visible under all circumstances).  
i) Maximum admissible pressure  (MAP) if it exceeds 1 MPa or 0.6 MPa for DN ≥ 500.  
j) Letter V or H, if the meter can only be operated in the vertical or horizontal position.  
k) The temperature class where it differs from T30 as specified in Table 4 of schedule 3 . 
l) The pressure loss class  where it differs from ∆𝑝 63 as specified in Table 8 of schedule 6 . 
m) The installation sensitivity class where it differs from U0/D0  as specified in schedule  6 
For a water meter with electronic devices, the following shall be applied where appropriate:  
n) For an external power supply: the voltage and frequency:  
o) For a replaceable battery: the latest date by which the battery shall be replaced:  
p) For a non -replaceable battery: the latest date by which the meter shall be replaced:  
q) Environmental classification:  
r) Electromagnetic environmental class. .  
 
The environmental classification and electromagnetic environmental class may be given on a 
separate datasheet, clearly  related to the meter by a unique identification, and not on the meter itself.  WORKING DRAFT OF 2nd March  2022 
  
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 SCHEDULE 5 
Table 6 - Rated Operating Conditions  
The rated operating conditions for a water 
meter shall be as follows. Flow rate range:   
Q1 to Q3 inclusive.  
 
Ambient temperature range:  +5 °C to +55 °C  
 
Water temperature range:  refer to Table 2 in schedule 1.  
 
Ambient relative humidity range:  0 % to 100  %, except for remote indicating 
devices where the range shall be 0 % to 93 %. 
  
Pressure range:  
 0.03 MPa (0.3 bar) to at least 1 MPa (10 bar), 
except for meters of DN ≥ 500, where the 
maximum admissible pressure (MAP) shall 
be at least 0.6 MPa (6 bar).  
 
Table 7 - Indicating range of a water meter  
Q3 Indicating range  
(minimum digits ) 
m3/h m3 
Q3 ≤6.3 9 999  
6.3 < Q3 ≤ 63 99 999  
63 < Q3 ≤ 630 999 999  
630 < Q3 ≤ 6300  9 999 999  
Table 6 may be expanded to larger values of Q3. 
 
 
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 SCHEDULE 6 
Table 8 - Pressure loss classes  
 
 
 
 
 
 
Note 1: The pressure loss is measured over the flow range Q1 ≤ Q ≤ Q3 
Note 2: For some meters, the highest pressure loss does not occur at Q3. 
 
Table 9 - Sensitivity to disturbances  in the upstream velocity field classes (U)  
Class  Required straight length × DN Straightener needed  
U0 0 No 
U3 3 No 
U5 5 No 
U10 10 No 
U15 15 No 
U0S 0 Yes 
U3S 3 Yes 
U5S 5 Yes 
U10S  10 Yes 
Table 10 - Sensitivity to disturbances  in the downstream velocity field classes (D)  
Class  Required straight length × DN Straightener needed  
D0 0 No 
D3 3 No 
D5 5 No 
D0S 0 Yes 
D3S 3 Yes 
                           
 
Minister of trade, Industry and Cooperatives  
 Class  Maximum pressure loss  
MPa  bar 
∆p 63 0.063  0.63 
∆p 40 0.040  0.40 
∆p 25 0.025  0.25 
∆p 16 0.016  0.16 
∆p 10 0.010  0.10 
HON. FRANCES MWEBESA