---
kind: "section"
citation: "40 C.F.R. § 141.533"
title: "40"
number: "141.533"
heading: "What data must my system collect to calculate a disinfection profile?"
url: "https://uscodex.org/cfr/40/141.533"
---

# §141.533. What data must my system collect to calculate a disinfection profile?


Your system must monitor the following parameters to determine the total log inactivation using the analytical methods in [§ 141.74 (a)](/cfr/40/141.74.md?p=a), once per week on the same calendar day, over 12 consecutive months:

- (a) The temperature of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow;
- (b) If your system uses chlorine, the pH of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow;
- (c) The disinfectant contact time(s) (“T”) during peak hourly flow; and
- (d) The residual disinfectant concentration(s) (“C”) of the water before or at the first customer and prior to each additional point of disinfection during peak hourly flow.

## Notes

### Source

Source: 67 FR 1839, Jan. 14, 2002, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-4, 300j-9, and 300j-11.

### Source

Source: 40 FR 59570, Dec. 24, 1975, unless otherwise noted.