12 Va. Admin. Code § 5-460-280
The chlorination equipment shall be operated so as to maintain a free chlorine residual content of not less than 0.5 ppm at all points throughout the swimming pool water when there are bathers present.
§ 35.1-13 of the Code of Virginia.
Derived from VR355-35-05 § 28, eff. March 1, 1962.