contains pathogenic bacteria

consists of undesirable substances rendering it unfit for drinking and domestic use

is safe and suitable for drinking and domestic use

is contaminated

dysentery

cholera

typhoid

maleria

carbon dioxide

oxygen

hydrogen

nitrogen

0.1 ppm

0.01 ppm

0.001 ppm

0.0001 ppm

0.1 mg/litre

1.5 mg/litre

5 mg/litre

10 mg/litre