Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 809 - Safe Drinking Water
Subchapter I - Maximum Contaminant Levels, Monitoring and Analytical Requirements for Primary Drinking Water Contaminants
Section NR 809.11 - Inorganic chemical maximum contaminant levels and BATs

(a) The maximum contaminant levels for nitrate and nitrite apply to both community water systems and non-community water systems, except as provided in sub. (3).

(b) The maximum contaminant level for fluoride only applies to community water systems.

(c) The maximum contaminant levels for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, mercury, nickel, selenium and thallium apply to community water systems and non-transient, non-community water systems.

(d) Compliance with maximum contaminant levels for inorganic chemicals is calculated under s. NR 809.117.

(a) The water will not be available to children under 6 months of age or any female who is or may become pregnant.

(b) The water supplier meets the public notification requirements under s. NR 809.958, including continuous posting of the fact that nitrate as nitrogen levels exceed 10 mg/l and the potential health effects of exposure.

(c) Local and state public health authorities will be notified annually of nitrate as nitrogen levels that exceed 10 mg/l.

(d) A supply of bacteriologically safe drinking water, containing less than 10 mg/l nitrate as nitrogen, is provided for infants less than 6 months of age and any female who is or may become pregnant.

(e) No adverse health effects will result.

(a) The best available technologies or BATs for achieving compliance with the maximum contaminant levels for the inorganic contaminants listed in sub. (2), except for fluoride, are as follows:

1 BAT only if influent Hg concentration.

2 BAT for Chromium III only.

3 BAT for Selenium IV only.

4 BATs for Arsenic V. Pre-oxidation may be required to convert Arsenic III to Arsenic V.

5 To obtain high removals, iron to arsenic ratio mus be at least 20:1.

Key to BATs in Table:

1 = Activated Alumina

2 = Coagulation/Filtration (not BAT for public water systems < 500 service connections)

3 = Direct and Diatomite Filtration

4 = Granular Activated Carbon

5 = Ion Exchange

6 = Lime Softening (not BAT for public water systems < 500 service connections)

7 = Reverse Osmosis

8 = Corrosion Control

9 = Electrodialysis

10 = Oxidation (Chlorine)

11 = Ultraviolet

12 = Oxidation/Filtration

13 = Alkaline Chlorination (pH >= 8.5)

(b) A water supplier may use an alternative treatment not listed in par. (a) if it is demonstrated to the department, using pilot studies or other means, that the alternative treatment is sufficient to achieve compliance with the MCLs in sub. (2).

(a) The EPA identifies the following table as the affordable technology, treatment technique, or other means available to public water systems serving 10,000 persons or fewer for achieving compliance with the maximum contaminant level for arsenic: -

Small Water System Compliance Technologies1 for Arsenic2

1 Section 1412(b)(4)(E)(ii) of the Safe Drinking Water Act or SDWA specifies that small water system compliance technologies must be affordable and technically feasible for small systems.

2 Small water system compliance technology for Arsenic V. Pre-oxidation may be required to convert Arsenic III to Arsenic V.

3 Section 1412(b)(4)(E)(ii) of the Safe Drinking Water Act or SDWA specifies 3 categories of small water systems: (i) those serving 25 or more, but fewer than 501, (ii) those serving more than 500, but fewer than 3,301, and (iii) those serving more than 3,300, but fewer than 10,001.

4 When POU or POE devices are used for compliance, programs to ensure proper long-term operation, maintenance, and monitoring must be provided by the water supplier to ensure adequate performance.

5 Unlikely to be installed solely for arsenic removal. May require pH adjustment to optimal range if high removals are needed.

6 Technologies reject a large volume of water-may not be appropriate for areas where water quantity may be an issue.

7 To obtain high removals, iron to arsenic ratio must be at least 20:1.

(b) The department may allow Point of Use (POU) treatment only if the department determines that treatment prior to entry to the distribution system is not feasible.