The designation of public water system treatment classifications shall be based on the following rating values:

PARAMETER RATING VALUE

1. (1) Surface Water Source

   1. (a) flowing stream 5
   2. (b) flowing stream with impoundment 7
   3. (c) raw water treatment 3

2. (2) Ground Water Source

   1. (a) first five wells 5
   2. (b) add 1 point per 5 wells or fraction thereof over 5 1

3. (3) Coagulation

   1. (a) aluminum sulfate, ferric chloride 10
   2. (b) polymer 5

4. (4) Mixing

   1. (a) baffle 2
   2. (b) mechanical 4
   3. (c) air 3

5. (5) Oxidation (pre‑treatment)

   1. (a) C1₂0₂ 5
   2. (b) ozone 5
   3. (c) KMn0₄ 3
   4. (d) C1₂ 3
6. (6) Carbon Treatment 2

7. (7) Aeration

   1. (a) mechanical draft 3
   2. (b) coke tray or splash tray 2
   3. (c) diffused 3
   4. (d) packed tower (VOC reduction) 10

8. (8) pH Adjustment (primary)

   1. (a) caustic (NaOH) 10
   2. (b) lime or soda ash 3
   3. (c) acid 10

9. (9) Sedimentation

   1. (a) standard rate 5
   2. (b) tube settlers 3
   3. (c) upflow 8
   4. (d) pulsators and plates 5
10. (10) Contact Tank 1

11. (11) Filtration

    1. (a) pressure

       1. (i) sand or anthracite 8
       2. (ii) synthetic media (birm) 8
       3. (iii) granular activated carbon (GAC) 9

    2. (b) gravity

       1. (i) sand 10
       2. (ii) anthracite (mixed) or GAC 12
       3. (iii) with surface wash or air scour 2
    3. (c) membrane 10

12. (12) Ion Exchange

    1. (a) softener, Na cycle 5
    2. (b) softener, H cycle 7
    3. (c) Fe and Mn (greensand) 9
    4. (d) mixed bed or split stream 9

13. (13) Lime Softening

    1. (a) spiractors 10
    2. (b) clarifier with coagulation 12
    3. (c) fuel burner (recarbonation) 5
14. (14) Phosphate (sequestering agent) 5

15. (15) Stabilization

    1. (a) acid feed 10
    2. (b) phosphate 2
    3. (c) caustic (NaOH) 10
    4. (d) lime or soda ash 3
    5. (e) contact units 5
16. (16) Reverse Osmosis, Electrodialysis 15

17. (17) Disinfection

    1. (a) gas C1₂ 10
    2. (b) hypochlorite solution 7
    3. (c) C1₂0₂(sodium chlorite and C1₂) 13
    4. (d) ozone 13
    5. (e) ammonia and C1₂ 12
    6. (f) ultraviolet light (uv) 5

18. (18) Fluoridation

    1. (a) saturator 8
    2. (b) dry feed 8
    3. (c) solution (acid) 10

19. (19) Pumping

    1. (a) raw 3
    2. (b) intermediate 1
    3. (c) finished 3
    4. (d) system booster 2

20. (20) Storage

    1. (a) raw 1
    2. (b) treated ground level tank 1
    3. (c) elevated in system (each extra tank 1 point) 2
    4. (d) hydropneumatic 2
21. (21) Population Served 1 point per 1,000 persons served 50 max
22. (22) Plant Capacity 1 point per 1 MGD capacity 25 max

23. (23) On‑Site Quality Control

    1. (a) bacteriological

       1. (i) MPN/MF 5
       2. (ii) HPC 2
       3. (iii) MMO‑MUG (Colilert) 2

    2. (b) pH

       1. (i) meter 2
       2. (ii) test kit 1

    3. (c) fluoride

       1. (i) meter 3
       2. (ii) colorimetric 3

    4. (d) chlorine

       1. (i) titrator 3
       2. (ii) colorimeter/spec. 2
       3. (iii) test kit 1
    5. (e) iron 1
    6. (f) hardness 1
    7. (g) alkalinity 1
    8. (h) turbidity 1
    9. (i) manganese 1
    10. (j) others (1 point each) 1
    11. (k) A.A. Spec, or G.C. Unit 5 each

History Note: Authority G.S. 90A‑21(c); 90A‑22;
Eff. February 1, 1976;
Readopted Eff. March 1, 1979;
Amended Eff. August 1, 2000; August 3, 1992; January 1, 1992; September 1, 1990;
Readopted Eff. September 1, 2018.