California Code of Regulations
Title 22 - Social Security
Division 4 - Environmental Health
Chapter 15 - Domestic Water Quality and Monitoring Regulations
Article 4 - Primary Standards-Inorganic Chemicals
Section 64431 - Maximum Contaminant Levels-Inorganic Chemicals
Public water systems shall comply with the primary MCLs in table 64431-A as specified in this article.
Table 64431-A
Maximum Contaminant Levels Inorganic Chemicals
| Chemical | Maximum Contaminant Level, mg/L | |
| Aluminum | 1. | |
| Antimony | 0.006 | |
| Arsenic | 0.010 | |
| Asbestos | 7 MFL* | |
| Barium | 1. | |
| Beryllium | 0.004 | |
| Cadmium | 0.005 | |
| Chromium | 0.05 | |
| Cyanide | 0.15 | |
| Fluoride | 2.0 | |
| Hexavalent chromium | 0.010 | |
| Mercury | 0.002 | |
| Nickel | 0.1 | |
| Nitrate (as nitrogen) | 10. | |
| Nitrate+Nitrite (sum as nitrogen) | 10. | |
| Nitrite (as nitrogen) | 1. | |
| Perchlorate | 0.006 | |
| Selenium | 0.05 | |
| Thallium | 0.002 |
* MFL=million fibers per liter; MCL for fibers exceeding 10 µm in length.
1. Amendment
of article heading, repealer of section and renumbering and amendment of former
section 64435 to section 64431 filed
9-8-94 as an emergency; operative 9-8-94 (Register 94, No. 36). A Certificate
of Compliance must be transmitted to OAL by 1-6-95 or emergency language will
be repealed by operation of law on the following day. For prior history, see
Register 88, No. 51.
2. Amendment of article heading, repealer of
section and renumbering and amendment of former section
64435 to section 64431 refiled
1-3-95 as an emergency; operative 1-3-95 (Register 95, No. 1). A Certificate of
Compliance must be transmitted to OAL by 5-3-95 or emergency language will be
repealed by operation of law on the following day.
3. Amendment of
article heading, repealer of section, and renumbering and amendment of former
section 64435 to section 64431 refiled
4-26-95 as an emergency; operative 4-26-95 (Register 95, No. 17). A Certificate
of Compliance must be transmitted to OAL by 8-24-95 or emergency language will
be repealed by operation of law on the following day.
4. Certificate
of Compliance as to 4-26-95 order transmitted to OAL 5-5-95 and filed 6-19-95
(Register 95, No. 25).
5. Amendment of subsection (a) and table
64431-A, repealer of table 64431-B and subsection (b) and amendment of NOTE
filed 3-23-98; operative 4-22-98 (Register 98, No. 13).
6. Amendment
of Table 64431-A and amendment of NOTE filed 5-13-2003; operative 6-12-2003
(Register 2003, No. 20).
7. Amendment of section and NOTE filed
9-18-2007; operative 10-18-2007 (Register 2007, No. 38).
8.
Amendment of subsection (a) -- Table 64431-A and amendment of NOTE filed
10-29-2008; operative 11-28-2008 (Register 2008, No. 44).
9.
Amendment of section and NOTE filed 5-28-2014; operative 7-1-2014 (Register
2014, No. 22).
10. Change without regulatory effect amending Table
64431-A and NOTE filed 7-16-2015 pursuant to section
100, title 1, California Code of
Regulations (Register 2015, No. 29).
11. Change without regulatory
effect amending Table 64431-A filed 9-11-2017 pursuant to section
100, title 1, California Code of
Regulations (Register 2017, No. 37).
Note: Authority cited: Sections 116271, 116293(b), 116350, 116365, 116365.5 and 116375, Health and Safety Code. Reference: Sections 116365, 116365.5 and 116470, Health and Safety Code.
The amended version of this section by Register 2024, No. 31, effective 10/1/2024 is not yet available.
