Md. Code Regs. 10.17.01.45 – Water Chemistry of a Pool and Spa.

A. An owner or operator shall ensure that the water chemistry of a public pool or spa is maintained according to the following requirements:

(1) The pH of the water is maintained between 7.2 and 7.8;
(2) The total alkalinity of the water is maintained between 60 ppm and 180 ppm;
(3) The calcium hardness of the water is maintained between 150 and 400 ppm;

(4) The Langelier Saturation Index of the water is maintained between -0.5 and +0.5 as calculated by:

(a) The Langelier Saturation Index formula: Langelier Saturation Index = pH + TF + CF + AF - 12.1 where: TF = temperature factor, CF = calcium hardness factor, and AF = alkalinity factor, and

(b) The following factor table:

Temperature (°F)	Temperature Factor	Calcium Hardness (ppm)	Calcium Factor	Total Alkalinity (ppm)	Alkalinity Factor
32	0.0	5	0.3	5	0.7
37	0.1	25	1.0	25	1.4
46	0.2	50	1.3	50	1.7
53	0.3	75	1.5	75	1.9
60	0.4	100	1.6	100	2.0
66	0.5	150	1.8	150	2.2
76	0.6	200	1.9	200	2.3
84	0.7	300	2.1	300	2.5
94	0.8	400	2.2	400	2.6
105	0.9	800	2.5	800	2.9
128	1.0	1000	2.6	1000	3.0

(5) The amount of total dissolved solids is maintained so that it does not exceed 1,500 ppm, except for a salt water pool where the total dissolved solids may not exceed 3,000 ppm;
(6) The amount of dissolved metals is maintained so that it does not exceed the following levels:
1. (a) Iron, 0.3 ppm,
2. (b) Manganese, 0.3 ppm, and
3. (c) Copper, 1.3 ppm; and
(7) The water clarity is maintained so that either a 6 inch seechi disc placed in the deepest part of a pool or spa or the main drain is clearly visible and sharply defined when observed from the side of the pool or spa.

B. An owner or operator shall ensure that:
1. (1) Water additives and treatment chemicals are used according to manufacturers' instructions; and
2. (2) When chemicals are added directly to a pool or spa, no one is allowed in the water until the chemicals are dissolved and diffused throughout the pool or spa.
C. An owner or operator shall ensure that the water temperature for a heated public pool or spa does not exceed:
1. (1) 88°F for a pool;
2. (2) 104°F for a spa; and
3. (3) 96°F for a therapy pool.

Authority: Health-General Article, §§2-102, 2-104, 18-102, and 20-303, Annotated Code of Maryland, and 15 U.S.C. §8003

Effective date: February 10, 1997 (24:3 Md. R. 187)

Chapter revised as an emergency provision effective July 1, 1999 (26:16 Md. R. 1238); amended permanently effective December 13, 1999 (26:25 Md. R. 1898)

Regulation .01A amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .02 amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .03 amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521)

Regulation .03A amended effective March 20, 2000 (27:5 Md. R. 584); December 19, 2005 (32:25 Md. R. 1942)

Regulation .04 amended as an emergency provision effective December 19, 2008 (36:4 Md. R. 345); amended permanently effective June 15, 2009 (36:12 Md. R. 837)

Regulation .04A, B amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .05B amended effective March 20, 2000 (27:5 Md. R. 584); December 19, 2005 (32:25 Md. R. 1942)

Regulation .05B amended as an emergency provision effective December 19, 2008 (36:4 Md. R. 345); amended permanently effective June 15, 2009 (36:12 Md. R. 837)

Regulation .05B amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521)

Regulation .05B amended effective November 2, 2020 (47:10 Md. R. 517); October 1, 2022 (49:12 Md. R. 640)

Regulation .06 amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521); November 2, 2020 (47:10 Md. R. 517)

Regulation .06-1 adopted effective November 2, 2020 (47:10 Md. R. 517)

Regulation .07 repealed and new Regulation .07 adopted effective November 2, 2020 (47:10 Md. R. 517)

Regulation .08 amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521)

Regulation .08 amended effective November 2, 2020 (47:10 Md. R. 517)

Regulation .09 amended effective November 2, 2020 (47:10 Md. R. 517)

Regulation .09C amended effective March 20, 2000 (27:5 Md. R. 584); December 19, 2005 (32:25 Md. R. 1942)

Regulation .10 amended effective November 2, 2020 (47:10 Md. R. 517)

Regulation .11C adopted effective November 2, 2020 (47:10 Md. R. 517)

Regulation .12B amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .13C amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .14A amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .15A amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .16C, D amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .17C, D amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .18A amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .21 amended effective October 1, 2022 (49:12 Md. R. 640)

Regulation .21B amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .22A amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .25B amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .25C amended effective March 20, 2000 (27:5 Md. R. 584)

Regulation .25G adopted effective November 2, 2020 (47:10 Md. R. 517)

Regulation .26 amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .27 amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .27F amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521)

Regulation .28 amended effective March 20, 2000 (27:5 Md. R. 584); December 19, 2005 (32:25 Md. R. 1942)

Regulation .28 amended as an emergency provision effective December 19, 2008 (36:4 Md. R. 345); amended permanently effective June 15, 2009 (36:12 Md. R. 837)

Regulation .28F, G amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521)

Regulation .28H amended effective November 2, 2020 (47:10 Md. R. 517)

Regulation .35A amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .40 amended effective March 20, 2000 (27:5 Md. R. 584); December 19, 2005 (32:25 Md. R. 1942)

Regulation .41B amended effective December 19, 2005 (32:25 Md. R. 1942)

Regulation .43 amended effective March 20, 2000 (27:5 Md. R. 584)

Regulation .43B amended effective November 2, 2020 (47:10 Md. R. 517)

Regulation .46 amended effective March 20, 2000 (27:5 Md. R. 584)

Regulation .53A amended as an emergency provision effective January 3, 2014 (41:2 Md. R. 88); amended permanently effective May 12, 2014 (41:9 Md. R. 521)

Regulation .55 adopted effective November 2, 2020 (47:10 Md. R. 517)