BISHTA issues the following advice regarding wood-fired (Scandinavian-type) hot tubs, as they are not considered suitable for 'business settings' (e.g. holiday parks and rentals) unless they are going to be drained and cleaned at least every 3 to 5 hours, depending on the water source used.
Scandinavian-type hot tubs are spas designed for single use of the water, where the water temperature is increased from an external heat source (such as a wood-fired stove) which is sited out of doors. The water is only to be left in the hot tub for a few hours before it needs to be drained.
This type of hot tub has no circulation and filtration system, and no chemical treatment for disinfection. They are also not equipped with automatic heating thermostats, and they require manual water temperature measurement and heating adjustment. They are not covered in the guidance set out in HSG 282.
The increased risks that can arise from the lack of disinfection and excessive water temperature include rapid bacterial growth (leading to infection) and scalding risk.
Depending on the water source used (potable or non-potable), the water should be held in the hot tub for a maximum of 5 hours for potable water (which complies with national water drinking regulations), or a maximum of 3 hours for non-treated and non-potable water (in accordance with Directive 2006/7/EC). When using swimmable water (not potable water) without any disinfection, the bathing time should not exceed one hour together with the heating time which should not exceed two hours to avoid growth of unwanted bacteria.
Also, the chimney heating the hot tub water is likely to get very hot and so these hot parts (especially the lowest 1,000 mm of the chimney) shall be protected from accidental contact (according to EN ISO 13732-1).
Please note that a new European standard on domestic spas and hot tubs (BS EN 17125) is expected to be published later this year that will provide more details on these type of hot tubs in business (or rented) settings.
For more information on using Wood-fired (Scandinavian-type) hot tubs in business settings, please contact BISHTA by phone on 01264-356211 or by email firstname.lastname@example.org.