For more general design, and construction requirements that pertain to all pools see WAC 246-260-031
(1) Walking surfaces. Owners shall design and maintain walking surfaces four feet or more wide around fifty percent or more of each spa pool. If spa pools are greater than one hundred square feet in surface area, then the entire perimeter must have a four-foot wide walking surface. If a spa has walking surfaces thirty inches or more in height above the floor, then they must have guardrails that conform with UBC codes.
(2) Spa pool structure. Owners shall ensure spa pool facilities have:
(a) White or light color surfaces, if a pool is one hundred square feet or more;
(b) Uniform floor slopes not exceeding one foot of drop in twelve feet of run sloped to drain;
(c) A minimum height of seven feet between the top of the pool rim and the ceiling;
(d) A maximum operational depth of four feet measured from the water line, except for special purpose designed pools; and
(e) Heater thermostat switches inaccessible to bathers.
(3) Spa capacity. The spa capacity is the maximum number of persons allowed in the spa pool at any one time and is the most restrictive of the following:
(a) The number of bathers able to be in the spa pool allowing ten square feet or more of water surface for each bather;
(b) Maximum bather load as calculated using the formula in subsection (4) of this section; or
(c) The capacity of the overflow system when using skimmers must be adequate to handle twenty gallons of displacement per bather.
(4) Turnover rate and bather load. Owners shall design and maintain water turnover of spa pool volume divided by turnover time divided by a constant (K). Spa turnover times are established in relation to loads as follows:
(a) Ten minutes for heavily loaded;
(b) Twenty minutes for moderately loaded;
(c) Thirty minutes for lightly loaded; and
(d) Sixty minutes for swim spas having very light loads.
Factors for Determination of Spa Loading
Turnover Time (options are 10, 20, 30, or *60 minutes)
Constant K10 (10 minute turnover time) 8 gpm/person
Constant K20+ (20, 30, or *60 minute turnover time) 6.67 gpm/person
60 minute turnover times are established for swim spa facilities.
(Constant K*) = Maximum spa capacity
Choose K based on turnover of the spa.
(5) Emergency equipment. Owners shall provide easily accessible first-aid and emergency equipment at all spa pool facilities during operating hours, including:
(a) A telephone within the facility for general use spa;
(b) A telephone within one-minute access for limited use spa pools;
(c) A standard sixteen-unit first-aid kit;
(d) A blanket reserved for emergency use; and
(e) A clearly marked emergency shutoff switch for turning off all pumps. The switch must be within twenty feet of each spa, accessible to the public, and triggering an audible alarm.