Table 4.
Disinfection data for chlorine and iodine to achieve 99.9% kill or inactivationa of select microorganisms.
| Chlorine | ||||||
|---|---|---|---|---|---|---|
| Organism | Concentration (mg·L−1) | Time (min) | pH | Temperature | Disinfection constantb | Reference |
| Escherichia coli | 0.1 | 0.16 | 6.0 | 5°C (41°F) | .016 | 141 |
| Campylobacter | 0.3 | 0.5 | 6.0–8.0 | 25°C (77°F) | 0.15 | 156 |
| 20 enteric virus | 0.5 | 60 | 7.8 | 2°C (36°F) | 30 | 142 |
| 6 enteric viruses | 0.5 | 4.5 | 6.0–8.0 | 5°C (41°F) | 2.5 | 160 |
| Norovirus | 1 | 10 | 6.0 | 5°C | 10 | 159 |
| 5 | 0.33 | 1.66 | ||||
| Hepatitis A virus | 0.36 | 6.5 | 6.0 | 5°C | 2.3 | 162 |
| Hepatitis A virus | 0.5 | 1 | 6.0 | 25°C (77°F) | 0.5 | 161 |
| Amebic cysts | 3.5 | 10 | 25°C (77°F) | 35 | 143 | |
| Giardia cysts | 2.5 | 60 | 6.0–8.0 | 5°C (41°F) | 150 | 144 |
| Giardia lamblia cysts | 0.85 | 90 | 8.0 | 2–3°C (36–37°F) | 77 | 145 |
| Giardia muris cysts | 3.05 | 50 | 7.0 | 5°C (41°F) | 153 | 165 |
| Cryptosporidium (2 strains) | 20 | 755 | 7.5 | 23°C | 15,300 | 168 |
| 20 | 501 | 7.5 | 23°C | 10,400 | ||
| Iodine | ||||||
| Escherichia coli | 1.3 | 1 | 6.0–7.0 | 2–5°C (36–41 °F) | 1.3 | 42 |
| Hepatitis Ac | 8 | 0.4 | 7.0 | 25°C | 3 | 146 |
| 8 | 1.1 | 7.0 | 5°C | 8.8 | ||
| Coxsackie virus | 0.5 | 30 | 7.0 | 5°C (41°F) | 15 | 147 |
| Amebic cysts | 3.5 | 10 | 25°C (77°F) | 35 | 143 | |
| Giardia cysts | 4 | 15 | 5.0 | 30°C (86°F) | 60d | 163 |
| Giardia cysts | 4 | 45 | 5.0 | 15° C (59°F) | 170d | 163 |
| Giardia cysts | 4 | 120 | 5.0 | 5°C (41 °F) | 480d | 163 |
a
99.9% is for comparison of disinfection potency and microorganism susceptibility. The standard for potable water is 99.99% inactivation for viruses and 99.999% for bacteria. This would be achieved in each example above with a higher concentration of disinfectant or a longer contact time.
b
Disinfection constant is the product of concentration (mg·L−1) and time (m), which are inversely related, and provides a single number for comparison for halogen susceptibility of microorganisms in specific water conditions.
c
Tested in purified water
d
More than 99.99% inactivation; viability tested only at 15, 30, 45, 60, and 120 min.