SPA ALERT

Spa operators need to be extra vigilant about safety standards, particularly in the light of recent incidents, says the independent Pool Water Treatment Advisory Group (PWTAG). Because of their high bather loads relative to water volume, spa pools are generally more difficult to keep clean and healthy than conventional pools - a fact that is recognised and dealt with in PWTAG's new book, Swimming Pool Water (details below). But a threat from Legionella has highlighted specific problems.

In at least two outbreaks recently, significant numbers of people have become ill (some fatally) from Legionnaires' disease linked to non-disinfected spa pools on display. One spa involved was in a UK garden centre; the other a flower show in Amsterdam. Both were running, unused by bathers, on display. Because no residual disinfectant was used, Legionella from stagnant water was introduced into the aerosol created by the water jets.

PWTAG Chairman Andy Elphick says the message is clear: ' Never run a spa without disinfectant, even on display. We understand that the particular UK spa design involved in one of these incidents has now been modified. But this is not necessarily true of imported spas. And any spa might harbour bugs in pipework where water is stagnant. All operators should understand that cramming customers into a small volume of very warm, turbulent water is a big challenge to the water treatment and circulation, as well as to management.'

PWTAG has other advice on spas:

• If the jets draw water from the spa, the outlets (sometimes referred to as pump inlets) must be arranged so as to minimise the risk of entrapment.
  
• Turnover periods for a commercial spa should be around 6 minutes.
• Good disinfection and filtration are as important as they are for swimming pools.
• Bathing loads and intervals betweeen sessions should be specified.
• The spa should be emptied at least daily and cleaned. The same applies to balance tanks.
• Spas should be shock-dosed with chlorine-based disinfectant after filling with fresh water.
• Filters should also be cleaned regularly. Sight glasses should be fitted to ensure that filter backwashing is effective. Flow meters allow turnover rates to be monitored.
• Disinfectant residuals and pH levels are critical. They should be checked manually before the spa is opened for the day, and as often as every two hours during use - depending on how heavily the spa is used and how effective the dosing control is.
• Microbiological monitoring is also important. Public Health Laboratory Service investigations found Pseudomonas aeruginosa, for example, in 40% of spas. Operators must be prepared to investigate and deal with directly any sources of infection.
• High velocities in the pipework will inhibit the build-up of biofilms that harbour microoorganisms. Pumps and air blowers should be run at least once a day for 30 minutes to clear any dead spots in the pipework.

SWIMMING POOL WATER Treatment & Quality Standards (ISBN 0 9517007 66) is £35 (UK), £45 (Overseas) including post and packing. It is 144 pages and distributed by Greenhouse Publishing (tel: +44 (0)1379 890721 or fax: +44 (0)1379 898244). Bulk supplies (in boxes of 33) are available from PWTAG's secretary.