DRAFT UGANDA STANDARD  
  DUS 2662  
First  Edition  
yyyy-mm-dd 
 
 
 Reference number  
DUS 2662 :2022  
© UNBS 2022   
  
Ceramic water filter— Specification  
 DUS 2662:2022  
ii © UNBS 2022  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct appl ication  
© UNBS 2022  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
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Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2662:2022  
© UNBS 2022  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  2 
4. Material  ................................ ................................ ................................ ................................ ...................  2 
5. Requirements  ................................ ................................ ................................ ................................ .........  3 
5.1 General requirements  ................................ ................................ ................................ ...........................  3 
5.2 Specific requirements  ................................ ................................ ................................ ...........................  3 
6 Packaging  ................................ ................................ ................................ ................................ ...............  4 
7 Labelling  ................................ ................................ ................................ ................................ .................  4 
8 Sampling  ................................ ................................ ................................ ................................ ................  5 
ANNEX A (normative)  Detection of internal cracks  ................................ ................................ .......................  6 
A.1 Principal  ................................ ................................ ................................ ................................ .................  6 
A.2 Procedure  ................................ ................................ ................................ ................................ ...............  6 
ANNEX B  (normative)  Determination of  rate of filtration  ................................ ................................ .............  7 
B.1 Apparatus  ................................ ................................ ................................ ................................ ...............  7 
B.2 Procedure  ................................ ................................ ................................ ................................ ...............  7 
ANNEX C (normative)  Method of test for presence of silver  ................................ ................................ ........  8 
C.1 Preparation of sample  ................................ ................................ ................................ ...........................  8 
C.2 Reagents  ................................ ................................ ................................ ................................ ................  8 
C.3 Procedure  ................................ ................................ ................................ ................................ ...............  8 
ANNEX D (normative)  Sampling and criteria for conformity  ................................ ................................ ........  9 
D.1 Lot ................................ ................................ ................................ ................................ ...........................  9 
D.2 Scale of sampling and criteria for conformity  ................................ ................................ ....................  9 
D.2.1 General  ................................ ................................ ................................ ................................ .......................  9 
D.2.2  Detection of internal cracks  ................................ ................................ ................................ .................  9 
D.2.3  Tests for Rat e of Filtration, Presence of Silver and all parameters for table 2  ...............................  9 
Bibliography  ................................ ................................ ................................ ................................ ......................  11 
 DUS 2662:2022  
iv © UNBS 2022  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of stand ards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of prepar ing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, priva te sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for app roval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC 301, Chemistry . 
 
 DUS 2662:2022  
© UNBS 2022  – All rights reserved  v 
 Introduction  
Globally, the world is expected to exceed the Millennium Development Goa l target of halving the proportion of 
people without access to safe drinking water by 2051   
Despite this, many  people still lack access to safe drinking water, leaving them vulnerable to diseases such as 
diarrhoea, typhoid and hepatitis. When people fall sick, local economies are affected and children stay home 
from school.  
Household water treatment and safe storage can dramatically improve drinking water quality, positively 
impacting the lives of those who rely on water from polluted rivers or lakes, or f rom unsafe wells or piped 
water supplies.  
Ceramic water filters are a low -cost, effective, simple and easily maintained method for water treatment at a 
household level (or “point of use”) – enabling families’ to access safe drinking water, free from diseas e-
causing pathogens.   
  
 
  
  
 DRAFT UGANDA STAND ARD  DUS 2662:2022  
 
© UNBS 2022  – All rights reserved  1 
 Ceramic water filter — Specification  
1 Scope   
This Draft Uganda Standard specifies the requirements , sampling and  test methods for ceramic water filter .  
2 Normative references   
The following referenced documents 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) ap plies.  
ISO 11923, Water quality — Determination of suspended solids by filtration through glass -fibre filters  
US ISO 10523, Water quality — Determination of pH  
US ISO 7887 , Water quality — Examination and determination of colour  
US ISO 7888, Water quality  — Determination of electrical conductivity  
US ISO 7027 –1, Water quality — Determination of turbidity – Part 1: Quantitative methods  
ISO 9308 -1, Water quality — Enumeration of Escherichia coli and coliform bacteria — Part 1: Membrane 
filtration method for waters with low bacterial background flora  
ISO 10359, Water quality -  Determination of fluoride   
ISO 11969, Water quality - Determination of arsenic  - Atomic absorption spectrometric method (hydride 
technique)  
ISO 12846, Water quality - Determination of m ercury - Method using atomic absorption spectrometry (AAS) 
with and without enrichment  
ISO 15681, Water quality - Determination of orthophosphate and total phosphorus contents by flow analysis 
(FIA and CFA)  
ISO 16266, Water quality  - Detection and enumerat ion of Pseudomonas aeruginosa ━ Method by membrane 
filtration  
ISO 21567, Microbiology of food and animal feeding stuffs ━ Horizontal method for the detection of Shigella 
spp. 
ISO 5961, Water quality -- Determination of cadmium by atomic absorption spectrom etry 
ISO 6222, Water quality -- Enumeration of culturable microorganisms ━ Colony count by inoculation in 
nutrient agar culture media  
ISO 6333, Water quality -- Determination of manganese -- Formaldoxime spectrometric method   
2 © UNBS 2022  – All rights reserved  
 ISO 6461, Water quality -- Dete ction ad enumeration of the spores of sulphite -reducing anaerobes (clostridia) 
━ Method by membrane filtration  
ISO 6777, Water quality -- Determination of nitrite -- Molecular absorption spectrometric method  
ISO 6785, Milk and milk products -- Detection of  Salmonella spp.  
ISO 6888, Microbiology of food and animal feeding stuffs ━ Horizontal method for the enumeration of 
coagulass -positive staphylococci (Staphylococcus aureus and other species)  
ISO 7890, Water quality -- Determination of nitrate -- Part 3: S pectrometric method using sulfosalicylic acid  
ISO 7899, Water quality -- Detection and enumeration of intestinal anterccocci  
ISO 8288, Water quality -- Determination of cobalt, nickel, copper, zinc, cadmium and lead -- Flame atomic 
absorption spectrometric  methods  
ISO 4832, Microbiology of food and animal feeding stuffs ━ Horizontal method for the enumeration of 
coliforms ━ Colony -count technique  
ASTM D 3866 -18, Standard Test Methods for Silver in Water  
  
3 Terms and definitions   
For the purposes of this document, the following terms and definitions apply.  
ISO and IEC mai ntain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp   
3.1  
ceramic  
brittle, corrosion and heat resistant, inorgani c non metallic material produced by h igh -temperature processing  
 
3.2 
firing  
controlled heat treatment of ceramic  ware in a kiln or furnace, during the process of manufacture, to develop 
the desired properties . 
 
3.3 
unglazed  
hard, dense material of homog eneous composition , deriving colour and texture from materials of which the 
body is made  
4. Material  
4.1  Ceramic  water filter shall be fired, unglazed porous ware and subsequently suitably treated chemically 
so that fine silver is embedded in the body of  the filter.  
4.2 The manufacturer shall provide a  suitable  food grade material for cleaning the ceramic filter.   DUS 2662:2022  
© UNBS 2022  – All rights reserved  3 
 5. Requirements  
5.1 General requirements   
5.1.1 Ceramic filter shall be properly fired so as not to shed particles under conditions of normal use. 
5.1.2 Ceramic filter  shall also be free from large discrete c avities, warpage, uneven firing and protrusion .  
5.1.3 Ceramic filter  shall no t have  visible external cracks .   
  
5.2 Specific requirements  
5.2.1  The ceramic water filter shall comply with the  specific requirement s given in table 1 when tested in 
accordance with the methods described therein . 
Table 1  — Specific  requirements for ceramic water filter  
S/No.  Parameter  Requirement  Test method  
i Detection of internal 
cracks  To pass test  Annex A  
ii Rate of filtration , l/hr  To pass test  Annex B 
iii Presence of Silver  To pass test  Annex C  
 
  
5.2.2  The ceramic water filter shall comply with the performance requirements done on the filtrate given in 
table 2 when tested in accordance with the methods de scribed therein . 
Table 2  — Performance requirements for the filtrate  
S/No.  Parameter  Requirement  Test method  
i Suspended matter  Not detectable  ISO 11923  
ii pH  6.5 – 8.5  US ISO 10523  
iii Conductivity , µS/cm, Max  1500  US ISO 7888  
iv Color , TCU, Max  15 US ISO 7887  
v Turbidity , NTU, Max  5 US ISO 7027 - 1  
vi Silver, mg/ L, max   0.1 ASTM D 3866 -18 
vii Arsenic, as As  0.01  ISO 11969  
viii Cadmium, as Cd  0.003  ISO 5961  
ix Lead, as Pb  0.01  
ISO 8288  x Copper, as Cu  1.000  
xi Mercury (total as Hg)  0.001 ISO 12846  
xii Manganese, as Mn  0.1 ISO 6333  
xiii Nickel, as Ni  0.02 ISO 8288  
xiv Nitrate as NO3 -  45  ISO 7890   
4 © UNBS 2022  – All rights reserved  
 xv Nitrite  0.003  ISO 6777  
xvi Phosphates, as PO43 -  2.2  ISO 15681  
xvii Fluoride, as F  1.5  ISO 10359  
xviii E.coli, in 100 mL  Absent  ISO 9308 - 1 
ISO 4832  xix Total coliforms, in 100 mL  Absent  
 
xx 
 Total viable counts at 22 ºC, in mL, 
max. a)  100    
ISO 6222  
Total viable counts at  
37 ºC, in mL, max. a)  50  
xxi Staphylococcus aureus in 100 mL  Absent  ISO 6888 -1  
xxii Sulph ite reducing anaerobes in100 mL  Absent  ISO 6461 -2  
xxiii Pseudomonas aeruginos a 
fluorescence in 100 mL  Absent  ISO 16266  
xxiv Streptococcus faecalis in 100mL  Absent  ISO 7899 -2  
xxv Shigella in 100 mL  absent  ISO 21567  
xxvi Salmonella in 100 mL  Absent  ISO 6785  
 
  
6 Pack aging 
Ceramic water filter shall be packaged in suitable containers that permits the product’s integrity.  
 7 Labelling  
7.1 The ceramic water filter shall be labelled  with the following information:  
a. Manufacturer’s name and the recogni zed trade -mark, if any;  
b. Rate of filtration , l/hr 
c. Lot number or batch number   
d. Country of origin and  
e. Physical address of the manufacturer  
7.2 The manufacturer shall provide an information leaflet with the following information  
a. Clean the ceramic water filter every 14 days  or when clogged.  
b. Scrub the ceramic water filter with clean water and a  suitable  food grade material , as provided by the 
manufacturer.  DO NOT use soap to clean the filter pot.  
c. Wash the bucket, tap and lid with clean water and soap  
d. Replace the ceramic wate r filter after two (2) years of use or when the filtration rate is  reduced.  DUS 2662:2022  
© UNBS 2022  – All rights reserved  5 
 8 Sampling  
The sampling procedure and the criteria for conformity shall be as given in Annex D 
  
6 © UNBS 2022  – All rights reserved  
 ANNEX A  
(normative ) 
 
Detection of internal cracks  
A.1 Principal  
This test is to detect internal cracks on the filter element  
A.2 Procedure  
A.2.1  submerge  a filtering element in water only u p to its rim, without letting water flow into the filter  
A.2.2  hold it for about 10 seconds to see if any water seeps through the walls of t he filter  
A.2.3  If water seeps through the walls of the filter after being submerged for the 10 seconds it is an 
indication of internal cracks and the filter has failed this test.  
 
 
 DUS 2662:2022  
© UNBS 2022  – All rights reserved  7 
 ANNEX B   
(normative ) 
 
Determination of rate of filtration  
B.1 Apparatus   
B.1.1  A calibrated T -Device is used to measure the change in water level  
B.1.2  A stop watch  
B.2 Procedure  
B.2.1 Soak  the filtering element for 24 hours  in a pool of water   
B.2.2 The soaked filter pots are removed from the pool and lai d on a raised platf orm [racks]  
B.2.3 Fill up the pot with clean water to full capacity  
B.2.4 A stopwatch  is set for one hour  
B.2.5 After one hour of filtration, the water level in litres per hour is read from the calibrated T -Device  
B.2.6 The acceptable rate of filtration shall be as declared by the manufacturer   
 
 
Figure B, showing the rate of filtration setup  
  
8 © UNBS 2022  – All rights reserved  
 ANNEX C 
(normative ) 
 
Method of test for presence of silver  
C.1 Preparation of sample  
Break the ceramic water filter, take sufficient quantity of pieces in agated pe stle and mortar and grind it to fine 
powder to give more than 5 g of powder.  
C.2 Reagents  
C.2.1  Dilute Nitric Acid 50 Percent (v/v)  
C.2.2 Dilute Hydrochloric Acid 35 Percent (v/v)  
C.2.3 Liquor Ammonia  
C.3 Procedure  
C.3.1  Take 5g of finely agated ceramic water filter material, wash with distilled water, allow the mixture  to 
settle  and decant the supernatant and wash out at least thrice and decant the supernatant liquid.  
C.3.2  Digest the residue with 50 ml of dilute nitric acid on a hot plate and allow settling .  
C.3.3  Decant the supernatant liquid into a suitable glass tube.  
C.3.4  Add into the glass tube a few m ills of dilute hydrochloric acid .  
C.3.5  If solution shows white turbidity, confirm presence of silver by adding an excess of liquid ammonia, 
when the turbidity will disappear  
  DUS 2662:2022  
© UNBS 2022  – All rights reserved  9 
 ANNEX D 
(normative ) 
 
Sampling and criteria for conformity  
D.1 Lot 
D.1.1 In a consignment all the ceramic water filters, manufactured from the same type of material and 
belonging to the same batch of manufacture shall be grouped t ogether to constitute a lot.  
D.1.2 Each lot shall be tested for conformity to the requirements of this standard.  
D.2 Scale of sampling and criteria for conformity  
D.2.1 General  
D.2.1.1  The number of ceramic water filters to be sampled from each lot depend s on the size of the lot 
and shall be as given in Table 3. 
D.2.1.2  These ceramic water filters shall be selected at random making use of random number tables.  
D.2.2 Detection of internal cracks  
D.2.2.1 The number of ceramic water filters to be sampled for examining the above parameter is given in 
col 3 of Table 3 
D.2.2.2  Any ceramic water filter failing in one or more of the tests shall be termed defective.  
D.2.2.3  The number of defective ceramic water filter shall not excee d the acceptance number ( col 4 of 
Table 3), if the lot is to be accepted under this clause.  
D.2.3 Tests for Rate of Filtration, Presence of Silver and all parameters for table  2 
D.2.3.1  The number of tests to be conducted for each of the above p arameters is given in col  5 of Table 
4. 
D.2.3.2 For conducting these tes ts, sample test pieces shall be obtained from the sample ceramic water 
filters as described in the respective test methods.  
D.2.3.3  No failures shall occur, if the lot is to be declared satisfactory under this clause  
 
 
  
10 © UNBS 2022  – All rights reserved  
 Table — 3 Scale of Sampling and Criteria for Conformity  
S/No.  Lot Size  Sample Siz e for 
detection of 
cracks  Acceptance No.  No. of tests for  rate of filtration, 
presence of silver and  all 
parameters for tables 2 and 3  
i Up to 25  3 0 1 
ii 26 to 50  5 0 1 
iii 51 to 100  8 1 2 
iv 101 to 200  13 1 3 
v 201 and above  20 2 4 
 
  
 
  
  DUS 2662:2022  
© UNBS 2022  – All rights reserved  11 
 Bibliography  
 
[1] IS 7402: 2011, Ceramic water purifier filter candles — specification (Second  Revision) . 
[2] IS 2781 : 2004 Glossary of terms relating to  ceramicware (second revision)  
[3] Justine Rayner (August 2009). Current Practices in Manufacturing of Ceramic Pot Filters for Water 
Treatment  
[4] Alemu Lelago Bulta1* and Geremew Arega W. Micheal2  ((2019). Evaluation of the efficiency of 
ceramic filters for water treatment in Kambata Taba ro zone, southern Ethiopia  DUS 2662: 2022  
© UNBS 2022  – All rights reserved  13 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by t he Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence o f this mark on a product or in relation to a produ ct is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are 
continu ally checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 2662 :2022    
 
ICS 81.060.20  
Price based on nn pages  
© UNBS 2022 – All rights reserved