This document outlines the Indian standards for drinking water quality. It lists 34 substances and characteristics that are tested, including turbidity, pH, iron, chloride, residual chlorine, dissolved solids, fluoride, arsenic and more. For each substance, it provides the desirable limit, undesirable effects outside that limit, and the permissible limit in the absence of alternate sources. All limits are set to ensure water remains safe for drinking and free from toxic or harmful levels of substances.

1. Indian Standards of drinking water
This chapter deals with the Indian standards for safe drinking water
Sl.
No.
Substance or
characteristic
Requirement
Desirable limit
Undesirable
effect outside the
desirable
Permissible
limit in the
absence of
alternate
Source
Remarks
Essential Characteristic
1.
Colour Hazen
Units, Max
5
Above 5,
consumer
acceptance
decreases
25
Extended to 25
only if toxic
Substance are
not suspect in
absence of
alternate
sources
2. Odour Unobjectionable - -
a) test cold and
when heated
b) test are
several
dilutions
3. Taste Agreeable - -
Test to be
conducted only
after safely has
been
established
4.
Turbidity
(NTU) Max
5
Above 5,
consumer
acceptance
decreases
10 -
5. pH value 6.5 to 8.5
Beyond this range
the water will
after the mucous
membrane and/or
No
relaxation
-

2. water supply
system
6.
Total
Hardness
(mg/L)
CaCO3
300
Encrustation in
water supply
structure and
adverse effects on
domestic use
600 -
7.
Iron (mg/L,
Fe) Max
0.3
Beyond this limit
taste/appearance
are affected; has
adverse effects on
domestic uses and
water supply
structure and
promotes iron
bacteria
1.0 -
8.
Chlorides 250
(mg/L, Cl)
Max
250
Beyond effects
outside the
desirable limit
1000 -
9.
Residual free
Chlorine
(mg/L), Max
0.2 - -
To be
applicable only
when water is
chlorinated.
Tested at
customer end.
When
protection
against viral
infection is
required, it
should be min.
0.5 mg/L.
Desirable Characteristics
10. Dissolved 500 Beyond this, 2000 -

3. solids mg/L.
Max
palatability
decreases and
may cause
gastrointestinal
irritation.
11.
Calcium
(mg/L, Ca)
Max.
75
Encrustation in
water supply
structure and
adverse effects on
domestic use.
200 -
12.
Magnesium
(mg/L, Mg)
Max
30
Encrustation in
water supply
structure and
adverse effects on
domestic use.
100 -
13.
Copper
(mg/L, Cu)
Max
0.05
Astringent taste
dis coloration and
corrosion of pipes
fittings and
utensils will be
caused beyond
this.
1.5 -
14.
Manganese
(mg/L, Mn)
Max
0.1
Beyond this limit
taste/appearance
are affected, has
advers effect on
domestic use and
water supply
structure
0.3 -
15.
Sulphate
(mg/L, SO4)
Max.
200
Beyond this
causes gastro
intestinal
irritation when
magnesium or
sodium are
400
May be
extended upto
400 provided
magnesium (as
Mg) does not
exceed 30

4. present
16.
Nitrate (mg/L,
NO3) Max.
45
Beyond this
methaemo
globinemia takes
place.
100 -
17.
Fluoride
(mg/L, F)
Max.
1.0
Fluoride may be
kept as low as
possible. High
fluoride may
cause fluorosis.
1.5 -
18.
Phenolic
Compounds
(mg/L
C6H5OH)
Max.
0.001
Beyond this, it
may cause
objectionable
taste and odour
0.002 -
19.
Mercury
(mg/L Hg)
Max
0.001
Beyond this the
water becomes
toxic
No
Relaxation.
To be tested
when pollution
is suspected
20
Cadmium
(mg/L, Cd)
Max
0.01
Beyond this the
water becomes
toxic
No
Relaxation.
To be tested
when pollution
is suspected
21.
Selenium
(mg/L, Se)
Max
0.01
Beyond this the
water becomes
toxic.
No
Relaxation.
To be tested
when pollution
is suspected
22.
Arsenic
(mg/L, As)
Max.
0.05
Beyond this the
water becomes
toxic
No
Relaxation
To be tested
when pollution
is suspected
23. Cyanide 0.05
Beyond this the
water becomes
toxic
No
Relaxation
To be tested
when pollution
is suspected

5. 24.
Lead (mg/L
Pb) Max.
0.05
Beyond this the
water becomes
toxic
No
Relaxation
To be tested
when pollution
is suspected
25.
Zinc (mg/L,
Zn) Max.
5
Beyond this limit
it can cause
astringent taste
and an
opalescence in
water
15
To be tested
when pollution
is suspected
26.
Anionic
detergents
(mg/L,
MBAS) Max
0.2
Beyond this limit
it can cause a
light froth in
water
1.0
To be tested
when pollution
is suspected
27.
Chromium
(mg/L, Cr6+)
0.05
May be
carcinogenic
above this limit
- -
28.
Polynuclear
Aromatic
Hydrocarbons
(mg/l, PAH)
Max
-
May be
carcinogenic
- -
29.
Mineral oil
(mg/L)
0.01
Beyond this limit,
undesirable taste
and odour after
chlorination takes
place
0.03
To be tested
when pollution
is suspected
30.
Pesticides
(mg/L) max
Absent Toxic 0.001 -
Radioactive materials
31. Alpha
emitters Bq/L
- - 0.1 -

6. Max
32.
Beta emitters
Pci/L Max
- - 1.0 -
33.
Alkalinity
(mg/L,) Max
200
Beyond this limit,
taste becomes
unpleasant
600 -
34.
Aluminum
(mg/L, Al)
Max
0.03
Cumulative effect
is reported to
cause dementia
0.2
35.
Boron (mg/L)
Max
1.0 - 5.0 -