Drinking water standards

• The World Health Organization
  
  The World Health Organization (WHO), set up some guidelines for drinking-water quality which are the international reference point for standards setting and drinking-water safety. The latest guidelines drew up by the WHO are those agreed to in Geneva, 1993.
  
  Click here for the WHO's drinking-water standards.
  
  You will notice that there is no guideline for some of the elements and substances which are taken into account. This is because there have not been sufficient studies about the effects of the substance on the organism, and therefore it is not possible to define a guideline limit. In other cases, the reason for a non-existing guideline is the impossibility of that substance to reach a dangerous concentration in water, due to its insolubility or its scarcity.

• The European Union
  
  The European Union drew up the Council Directive 98/83/EC on the quality of water intended for human consumption, adopted by the Council on 3 November 1998. This was drawn up by reviewing the parametric values of the old Drinking Water Directive of 1980, and strengthening them where necessary in accordance with the latest available scientific knowledge (WHO guidelines and Scientific Committee on Toxicology and Ecotoxicology). This new Directive provides a sound basis for both the consumers throughout the EU and the suppliers of drinking water.
  
  These were the main changes in the parametric values:

- Lead: The guideline was reduced from 50 µg/l to 10 µg/l, and a transition period
of 15 years was defined to allow replacing of lead distribution pipes.

- Pesticides: The values for individual substances and for total pesticides were
retained (0.1µg/l / 0.5µg/l), plus additional, more stringent values were
introduced for certain pesticides (0.03µg/l).

- Copper: The value was reduced from 3 to 2 mg/l.

- Some new standards were introduced for new parameters like trihalomethanes,
trichloroethene and tetracholoroethene, bromate, acrylamide etc.

EU's drinking water standards

Council Directive 98/83/EC on the quality of water intented for human consumption. Adopted by the Council, on 3 November 1998:

Chemical parameters

Parameter	Symbol/formula	Parametric value (mg/l)
Acrylamide	C3H5NO	0.0001
Antimony	Sb	0.005
Arsenic	As	0.01
Benzene	C6H6	0.001
Benzo(a)pyrene	C20H12	0.00001
Boron	B	1.00
Bromate	Br	0.01
Cadmium	Cd	0.005
Chromium	Cr	0.05
Copper	Cu	2.0
Cyanide	CN =	0.05
1,2-dichloroethane	Cl CH2 CH2 Cl	0.003
Epichlorohydrin	C3H5OCl	0.0001
Fluoride	F	1.5
Lead	Pb	0.01
Mercury	Hg	0.001
Nickel	Ni	0.02
Nitrate	NO3	50
Nitrite	NO2	0.50
Pesticides		0.0001
Pesticides - Total		0.0005
PAHs	C2 H3 N1 O5 P1 3	0.0001
Selenium	Se	0.01
Tetrachloroethene and trichloroethene	C2Cl4/C2HCl3	0.01
Trihalomethanes - Total		0.1
Vinyl chloride	C2H3Cl	0.0005

Indicator parameters

Parameter	Symbol/ formula	Parametric value
Aluminium	Al	0.2 mg/l
Ammonium	NH4	0.50 mg/l
Chloride	Cl	250 mg/l
Clostridium perfringens (including spores)		0/100 ml
Colour		Acceptable to consumers and no abnormal change
Conductivity		2500 μS/cm @ 20oC
Hydrogen ion concentration	[H+]	≥ 6.5 and ≤ 9.5
Iron	Fe	0.2 mg/l
Manganese	Mn	0.05 mg/l
Odour		Acceptable to consumers and no abnormal change
Oxidisability		5.0 mg/l O2
Sulfate	SO4	250 mg/l
Sodium	Na	200 mg/l
Taste		Acceptable to consumers and no abnormal change
Colony count 22o		No abnormal change
Coliform bacteria		0/100 ml
Total organic carbon (TOC)		No abnormal change
Turbidity		Acceptable to consumers and no abnormal change
Tritium	H3	100 Bq/l
Total indicative dose		0.10 mSv/year

Microbiological parameters

Parameter	Parametric value
Escherichia coli (E. coli)	0 in 250 ml
Enterococci	0 in 250 ml
Pseudomonas aeruginosa	0 in 250 ml
Colony count 22oC	100/ml
Colony count 37oC	20/ml

Radionuclides

Contaminant	MCLG1(mg/L)2	MCL orTT1(mg/L)2	Potential Health Effects from Long-Term Exposure Above theMCL (unless specified as short-term)	Sources of Contaminant in Drinking Water
Alpha particles	none7 ---------- zero	15 picocuries per Liter (pCi/L)	Increased risk of cancer	Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation
Beta particles and photon emitters	none7 ---------- zero	4 millirems per year	Increased risk of cancer	Decay of natural and man-made deposits of certain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation
Radium 226 and Radium 228 (combined)	none7 ---------- zero	5 pCi/L	Increased risk of cancer	Erosion of natural deposits
Uranium	zero	30 ug/L as of 12/08/03	Increased risk of cancer, kidney toxicity	Erosion of natural deposits

National Secondary Drinking Water Regulations

National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.
• National Secondary Drinking Water Regulations - The complete regulations regarding these contaminants available from the Code of Federal Regulations Web Site.
• For more information, read Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals.

List of National Secondary Drinking Water Regulations

Contaminant	Secondary Standard
Aluminum	0.05 to 0.2 mg/L
Chloride	250 mg/L
Color	15 (color units)
Copper	1.0 mg/L
Corrosivity	noncorrosive
Fluoride	2.0 mg/L
Foaming Agents	0.5 mg/L
Iron	0.3 mg/L
Manganese	0.05 mg/L
Odor	3 threshold odor number
pH	6.5-8.5
Silver	0.10 mg/L
Sulfate	250 mg/L
Total Dissolved Solids	500 mg/L
Zinc	5 mg/L