Page 12: Guidelines for Canadian Drinking Water Quality: Guideline Technical Document - Enteric Protozoa: Giardia and Cryptosporidium

Appendix B: CT tables for the inactivation of Cryptosporidium oocysts by chlorine dioxide and ozone at various temperatures

Table B.1. CT values (in mg·min/L) for inactivation of *Cryptosporidium* oocysts (U.S. EPA, 2006a)
Log inactivation^{Table 1 Footnote a}	Water temperature (°C)
Log inactivation^{Table 1 Footnote a}	≤ 0.5	1	2	3	5	7	10	15	20	25	30
0.25	159	153	140	128	107	90	69	45	29	19	12
0.5	319	305	279	256	214	180	138	89	58	38	24
1	637	610	558	511	429	360	277	179	116	75	49
1.5	956	915	838	767	643	539	415	268	174	113	73
2	1275	1220	1117	1023	858	719	553	357	232	150	98
2.5	1594	1525	1396	1278	1072	899	691	447	289	188	122
3	1912	1830	1675	1534	1286	1079	830	536	347	226	147
Table 1 Footnotes Table 1 Footnote 1 Log inactivation = (0.001506 × (1.09116)^Temp) × CT (U.S. EPA, 2006a). Return to Table 1 footnote a referrer

Table B.2. CT values (in mg·min/L) for inactivation of *Cryptosporidium* oocysts (U.S. EPA, 2006a)
Log inactivation^{Table 1 Footnote a}	Water temperature (°C)
Log inactivation^{Table 1 Footnote a}	≤ 0.5	1	2	3	5	7	10	15	20	25	30
0.25	6	5.8	5.2	4.8	4	3.3	2.5	1.6	1	0.6	0.39
0.5	12	12	10	9.5	7.9	6.5	4.9	3.1	2	1.2	0.78
1	24	23	21	19	16	13	9.9	6.2	3.9	2.5	1.6
1.5	36	35	31	29	24	20	15	9.3	5.9	3.7	2.4
2	48	46	42	38	32	26	20	12	7.8	4.9	3.1
2.5	60	58	52	48	40	33	25	16	9.8	6.2	3.9
3	72	69	63	57	47	39	30	19	12	7.4	4.7
Table 1 Footnotes Table 1 Footnote 1 Log inactivation = (0.0397 × (1.09757)^Temp) × CT (U.S. EPA, 2006a). Return to Table 1 footnote a referrer