LEGIONELLA - World Health Organization

Table . Example of a water safety plan overv ew for a hot tub (commerc al context)
Process step P pework Water n hot tub
Assess
hazards and
pr or t ze r sks
(example)
↓
Ident fy control
measures
(example)
↓
Mon tor
control
measures
(example)
↓
Prepare
management
procedures
(example)
Establ sh
ver f cat on
and
surve llance
(example)
Stagnant water
in deadlegs in the
pipework, resulting
in proliferation of
legionellae
Routine cleaning
procedures and
review of system
flow diagram
Routine review
of process flow
diagram to
identify areas
of concern or
stagnation
Removal of
deadlegs where
possible
• Sweat, urine, faecal matter and personal care
products washed off bathers’ bodies in tub,
providing a nutrient source for legionellae
• Proliferation of legionellae in air-conditioning units
in the hot tub room
• Rest period programmed during hot tub operation to
discourage excessive use and to allow disinfectant
levels to recover
• Constant circulation of water in hot tub and
replacement of at least half the water in each
hot tub at least daily
• Signage to encourage bathers to shower before hot
tub use and to inform them of proper use of facilities
• Filtration monitored by pressure and observation
• Cleanliness of hot tub surroundings monitored
by observation
• Maintaining and physically cleaning heating, ventilation
and air-conditioning systems serving the hot tub
room (e.g. weekly to monthly)
• Inspection of backwash filters at least daily or
on pressure drop
• Inspection of cleanliness of hot tub surroundings
at least daily (depending on frequency of use)
• Testing regime for chemical and microbial
parameters (pH and active biocide) at least twohourly
in a heavily used spa in commercial premises
• Clean or replace backwash filters
• Clean pool surroundings
• Close facility if necessary
• Internal audit and external audit (by the health department) to confirm
that operational monitoring and corrective actions are being undertaken
as stated in the WSP
• Monthly heterotrophic colony counts at the tap and in the source water
(to track trends and changes, rather than as an absolute indicator, and
to be undertaken by an accredited laboratory)
• Three-monthly sampling for legionellae in the pipework
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS