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By Email 
Our Ref: 09/09/26/lk/325 
Health Protection Agency
 
Communications 
 
Public Information Access 
Mr Michael Jones 
61 Colindale Avenue 
London 
[email address] 
NW9 5DF 
 
Tel +44 (0)20 8327 6629 
 
Fax +44 (0)20 8327 6633 
 
 
www.hpa.org.uk 
26 October 2009 
Email: [Health Protection Agency request email] 
 
 
Dear Mr Jones 
 
Re:  Chloramine in tap water – is it safe? 
Thank you for your Freedom of Information request dated 26 September regarding 
Chloramine in tap water. Under section 1 (1) (a) of the Freedom of Information Act, I 
can confirm that the Health Protection Agency (HPA) does hold some of the 
information you require. 
 
Disinfection of drinking water is an important public health measure and public water 
suppliers in the UK are required to disinfect the water that they supply. This is 
fundamental to preventing the spread of waterborne diseases, such as cholera.  
 
Background 
Chloramine is primarily used as a residual disinfectant for public drinking water 
supply and is formed by the reaction of ammonia with chlorinated water. 
Monochloramine is the predominant chloramine compound produced, with only 
traces of other chloramines. 
 
The HPA does not hold any information on the health risks of chloramine used to 
disinfect the public water supply other than that which is already in the public domain. 
The HPA was not involved in any risk assessment prior to the introduction of 
chloramination for disinfecting the public drinking water supply in England and Wales 
and has not subsequently been asked to do so. The HPA endorses the opinion of the 
World Health Organization (WHO) and its recommended Guideline Value (GV) Afor 
monochloramine in drinking water. The WHO GVs are subject to rolling revision in 
the light of new information. The WHO is an independent international authority that 
conducts expert evaluations on the health risks of chemicals in drinking water. The 
WHO drinking water GVs are generally used as a basis for European and national 
Member States regulatory standards for drinking water. A WHO background 
document on the toxicity data for monochloramine and basis of derivation of the 
monochloramine GV is available. 
                                                  
A A GV represents the concentration of a compound that does not result in any significant risk to health 
of the consumer over a lifetime of consumption 
 
 
 
http://www.who.int/water_sanitation_health/dwq/chemicals/en/monochloramine.pdf 
 
The HPA endorses the WHO health risk assessment of monochloramine in drinking 
water and the recommended GV of 3 mg L -1. Consequently, we consider that the 
consumption of chloraminated tap water at concentrations not exceeding GV of 3 mg 
L -1 monochloramine is not expected to result in any appreciable risk to health. 
Inadequate disinfection of drinking water is likely to result in a substantial risk to 
health. 
 
Lead pipes 
The question of whether chloramine affects the release of lead from lead pipes is a 
matter for the Drinking Water Inspectorate (DWI) rather than the HPA. However, it is 
correct that lead is a neurodevelopmental toxin and that exposure can lead to 
cognitive defects, such as reduced IQ in children (HPA, 2007) 
 
Anaemia 
Regarding anaemia, the HPA is not aware of any specific studies that have linked 
chloramine with anaemia in children. Adverse effects on red blood cells such as 
acute haemolytic anaemia and methaemoglobinaemia have been reported in 
haemodialysis patients when tap water containing chloramine was used in dialysis. 
However, this dialysed route of exposure is not relevant to the exposure to the 
general public to drinking water (WHO, 2004a). for example, when exposed via 
drinking, humans consume small volumes of chloraminated water relative to the 
volume of red blood cells exposed (IPCS, 2000) 
 
Rectal and bladder cancer 
There have been a number of epidemiological studies that have associated 
chlorinated drinking water with bladder and colon cancer (WHO, 2004a). However, 
the HPA is not aware of any epidemiological studies specifically on chloraminated 
drinking water that have been associated with an increase risk of bladder or rectal 
cancer. The WHO considered that the available animal data do not support an 
association between the occurrence of this cancer and chloraminated drinking water 
(WHO, 2004a). Furthermore, monochloramine is not considered to represent a 
genotoxic hazard to humans i.e. it is not considered to have the potential to damage 
the genetic material (WHO, 2004a). Genotoxic substances can cause a mutation in 
the DNA, which in theory over time could lead to cancer. 
 
The international Agency for Research on Cancer (IARC) considers that chloramine 
is not classifiable as to its human carcinogenicity as there is inadequate human and 
animal evidence to make the assessment (IARC, 2004) 
 
I hope you have found this information useful, however, if you are dissatisfied with 
this response and would like a copy of the HPA complaints procedure then please 
contact Mr George Stafford, Complaints Manager at: Health Protection Agency, 61 
Colindale Avenue, London NW9 5EQ. 
 
 
Please note that you have the right to an independent review by the Information 
Commissioner’s Office if a complaint cannot be resolved through the HPA complaints 
procedure. The Information Commissioner’s Office can be contacted by writing to 
Information Commissioner’s Office, Wycliffe House, Water Lane, Wilmslow, Cheshire 
SK9 5AF. 
 
Please contact me if you require any further information or assistance. 
 
Yours sincerely 
Leigh Kelly 
Freedom of Information Officer 
Health Protection Agency 
 
References 
 
HPA 2007. Health Protection Agency Compendium on Lead – Toxicological overview 
http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1194947332124 
 
IPCS 2000. The International Programme on Chemical Safety (IPCS). Environmental 
Health Criteria 216. Disinfectants and disinfection by-products. WHO, 2000. 
http://www.inchem.org/documents/ehc/ehc/ehc216.html 
 
The International Agency for Research on Cancer (IARC) 2004 – Summaries and 
evaluations. Chloramine. 
http://www.inchem.org/documents/iarc/vol84/84-02-chloramine.html 
 
Plewa M et al., 2008. Occurrence, synthesis and mammalian cell cytotoxicity and 
genotoxicity of haloacetamides: An emerging class of nitrogenous drinking water 
disinfection by-products. Environmental Science and Technology, 41 (2), 955-961. 
 
Richardson S et al., 2007. Occurrence, genotoxicity, and carcinogenicity of regulated 
and emerging disinfection by-products in drinking water; A review and roadmap for 
research. Mutation Research, 636, 178-242. 
 
 

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