(1) Spa operators must drain, thoroughly clean, and disinfect the spa:

(a) weekly; or

(b) when the total dissolved solids reach 1500 ppm above the levels in the potable water supply used for the spa; or

(c) when required as determined by using the following formula: number of spa gallons divided by three divided by the number of bathers in a 24-hour period equals the number of days before draining, cleaning, and disinfecting the spa is required.

(2) The operator must document the date the spa was drained and cleaned and whether the spa is drained and cleaned weekly or based upon the criteria in (1)(b) or (c). If the spa is drained and cleaned based upon total dissolved solids, that reading must be documented. If the spa is drained and cleaned based upon the size of the spa and the number of users, the licensee must maintain records showing the number of users in each 24-hour period.