POOL SCARES REINFORCE THE NEED FOR GOOD OPERATING STANDARDS

This summer's media stories about problems with swimming pools should alert pool managers and the public to the importance of following established guidelines, according to the source of such guidelines, the independent Pool Water Treatment Advisory Group (PWTAG). Swimming Pool Water, PWTAG's authoritative book on the subject, details the procedures that should guarantee healthy pool water and pool hall atmospheres. These involve close attention to issues like controlling bathing load, monitoring chemical levels and ventilation.

PWTAG Chairman Ralph Riley does not dismiss the problems. "Certainly the Belgian study linking swimming pools with childhood asthma is a serious piece of work, although both we and the Department of Health committee that has examined the it have a number of questions about the way the research was done. And given that asthma is on the increase in all age groups, while pool water and air quality is improving, we are confident that pools are not responsible. But there's no doubt that nitrogen trichloride and other combined chlorines need to be kept at a minimum. The mechanisms to ensure this are well established.

"Newspaper investigations claim to have identified pools where bug levels are higher than they should be. Again, there are doubts about the research - in particular, sampling methodology. It is certainly possible for a pool that's been hit with unexpected pollution, or whose systems have failed, to get a poor microbiological result. The test would be repeated and checks made in the meantime to ensure everything is working as it should. Again, operators need be in no doubt how to do this. All pools following our guidelines should be monitoring the water continually to prevent problems. And since PWTAG started issuing its guidance and setting pool water quality standards for swimming pools, I'm confident that there has been a marked improvement in pool water standards in the UK."

Designing and operating a good pool demands attention to a combination of many factors; these are brought together in the PWTAG book, Swimming Pool Water. They can be summarised.

• The pool should have a bathing load appropriate to the pool's size, use, circulation rate and turnover. This bathing load should not be exceeded.
  
• The pollution introduced to the pool by bathers should be minimised -- including positively encouraging all bathers to shower before they swim.
  
• Disinfection and dosing are best controlled continuously by automatic monitors. In any case, strict control of bathing load and regular monitoring (every 2 hours in most pools) should ensure that combined chlorine levels are minimised - ideally zero, usually under 1mg/l and certainly less than half the free chlorine figure.
  
• Free chlorine itself should be maintained as low as is compatible with good results from microbiological testing (monthly tests for all pools). Figures as low as 0.5-1mg/l (for chlorine gas and hypochlorites) should be sufficient in a well-designed and well-run pool. This may mean keeping pH values down to about 7.2 to make the chlorine really effective and using ozone or ultraviolet as extra plantroom treatment (to enhance the water quality).
  
• Pool halls should be properly ventilated. This means at least 12 litres of fresh air per second to refresh the air on and above the surface of the water for everyone there - and no recirculation of stale air when the pool is being used by bathers.
  
• Underpinning all this, staff responsible for maintaining water quality should be well trained and competent, working to established, approved procedures under the direction and guidance of knowledgeable, responsible management.

There is no doubt that pools which don't follow such guidelines are more likely to have bugs; also unacceptable levels of chloramines in the water and air - known to be irritating, even if their role in asthma is less certain.

Although PWTAG is happy that its guidelines are the key to good pools, it is not happy that they are only guidelines. Ralph Riley says PWTAG would like to see them enshrined in regulations. "For years we have tried to get the government interested in regulating pools. We haven't given up, but as a step in that direction we have arranged for the British Standards Institution to publish a Code of Practice, based on Swimming Pool Water. We hope that this will encourage the better pools to parade their excellence and shame the less good ones into the necessary improvements".

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.