Working in a weakly regulated industry

A few years ago I was interviewed by ‘Holidays from Hell’ a television program dedicated to showing all that was bad about foreign holidays. I was working in Bournemouth at the time but due to hastily applied imitation sun stuff and surrounded by bright lights and a golf umbrella, even my nearest and dearest believed I was out there ‘living it large’ in the Balearics.

The problem there was a debilitating outbreak of Cryptosporidiosis from a single celled life form that can be released in liquid faecal matter by most vertebrates, birds, fish, animals, reptiles and of course humans. Haven’t we all heard the advert, “kills 99% of known germs” well this is part of the remaining 1%, plus its bigger, well hard cousin Giardia.

So a vertebrate released it into the water where it can live for up to six months and due to its size, about six microns (approx. 1/16th of the thickness of a human hair) it will pass straight through any filter that is not using a flocculant and back into the pool. The World Health Organisation (WHO) in their recent publication, ‘Guidelines for Safe Recreational Water Environments’ state that each bather will swallow on average 100 millilitres of water. Who is most likely to do that? Young kids whale spouting, but also research indicates adults also swallow the water when bathing. When released into the water it will form a hard impervious shell (oocyst) and these are resistant to the levels of chlorine generally found in swimming pools and spa baths.

These oocysts, when ingested are immediately infectious at relatively low doses (10 or above oocysts swallowed can cause the disease in humans).Well personally I don’t want to swallow my own faecal matter, but certainly not someone who I had not been introduced to (and even then I would have to know them frightfully well). These oocysts attach themselves to cells of the small bowel. The shell is broken down by the bodies acidic gastric juices and out pops the protozoan and invade the cells of the intestine. Incubation period is commonly 5-10 days but has been known to be as long as 28 days.

The symptoms are similar to Cholera, sweating, shivering, nausea, stomach cramps, sickness and Diarrhea (10 pints of lager and a kebab provide similar effects with me).

Generally we rely on our immunity system to fight it and this may take over a week. If your immunity system is compromised in rare cases it can be fatal. It has been estimated by some legal companies that the compensation paid out over the Balearics incident was in excess of £3,000,000 to 1900 claimants. This made a mockery of the £40.00 per sufferer originally offered by the holiday company.

Not just me but many others in the pool industry spent the Autumn of that year chasing around pools that had been cross contaminated by those still infected after returning from the Balearics and I personally dealt with several pools that had to be emptied and subjected to various forms of treatment including sand changes, treatment with Chlorine Dioxide, thermal sanitisation, Ozone, Ultra Violet, etc. etc. Haven’t we all heard announcements in the media after problems with the water supply that all water for drinking should first be boiled. Now you know why!

In the Milwaukee, USA outbreak back in 1993, over 400, 000 people displayed symptoms with over 100 deaths attributed to it from a population of 1,600,000, this was not from a swimming pool but from the water supply from Lake Michigan.

The investigation following the outbreak revealed that following large rainfall in the spring a sewerage treatment plant had overflowed into the lake. This contaminated the water going into the southern part of the lake which fed the Milwaukee southern water treatment plant. One of the problems of establishing when had the water been contaminated was resolved when a southern Milwaukee ice maker called saying that he had two 50 gallon (228 litre) blocks of ice created for ice sculptures on two separate days during the period of interest. When the ice was melted and tested, it was confirmed that Cryptosporidium was present in the water.

What made it worse was during that period, people drunk tap water, got diarrhea, used the toilet, the contaminated sewage went back to the treatment works where once again it overflowed into the lake exacerbating the situation still further. Guaranteed cyst free water is on sale at vending machines in many shopping malls in the USA. Recently and for about $120 dollars a hand held, battery powered, UV device has gone on sale, designed to make drinking water safe.


How is Crypto identified?

Analysis is by examination of a faecal sample.


Is there a prescription drug that is successful against it?

In the USA there is nitazoxanide for treatment of cryptosporidiosis, basically this will target the Diarrhea and its success rate is between 70 to 90%. It was originally for children aged 1-11 years but since 2004 it was also licensed for older children and adults. However anti-retroviral drugs, can also produce dramatic improvements. Patients however can stay infectious for a considerably longer periods and this is why it is strongly advocated that after suffering diarrhea do not use a pool or spa bath for at least two weeks following resolution of symptoms.

Many studies were undertaken followed the initial Milwaukee investigation. Shortly after the outbreak, public pools throughout the USA were reported as sources of outbreaks. This occurred because people from Milwaukee who were reporting symptoms traveled to other parts of the country during their Spring break and swam in pools, where chlorine alone could not kill the protozoans.

This brings me back to the present day and recently a report over a Scottish pool that experienced a Crypto outbreak following the Balearics incident has now been released into the public domain. I’m sure that this pool complex is now one of the safest to swim in, in the UK as I have always noticed after a major incident, these operators religiously follow all guidance ‘to the letter’.

In the August and September of that year there were approximately 50 cases of cryptosporidium associated with this pool. Following this, the pool was closed towards the middle of September and an outbreak team was formed.

The team concluded that the outbreak was due to bathers being exposed to contaminated water from the pool due to what was described as a ‘multi-factorial failure’ of the pools water treatment plant system.



  • The filters had been refurbished in 2000 but investigation indicated the installation was seriously sub-standard.
  • Flow rates were poor and were not monitored.
  • The meters had not been calibrated.
  • The inlet points did not distribute the water to all areas of the pool resulting in areas of poor water refreshment.
  • The scum channel drainage system due to poor design allowed water to stagnate in this area and furthermore allowed the introduction of air into what should be an air-free system.
  • Coagulant dosing was weekly instead of continual addition.
  • The filters were not ‘fit for purpose’ due to the quality of the filter media (it contained many sea shells).
  • It lost sand into the pool due to faulty ‘laterals’.
  • The filter concrete was extensively damaged.
  • The interiors of the filters were not annually inspected.
  • The surface of the sand in the filter was not level and this indicated that backwashing was not vigorous enough to fluidise the filter bed.
  • This was even with air scouring that was deemed also as being inadequate.


It is probable that the introduction of cryptosporidium into this pool was by bathers who used the pools had holidayed in the Balearics in early August, and were still infectious. The outbreak team however took the view that the poor condition of the pool’s water treatment plant was the major cause of this outbreak, an accident waiting to happen!

This they said was compounded by the difficulties and inadequacies of implementing controls in a weakly regulated industry. The combination of non-enforceable guidelines (PWTAG) and the risks of outbreaks also being increased if contracts for swimming pool related works are poorly specified and often rely solely on price.


What should we do as a minimum?

  • Educate our customers by signage
  • Positively encourage a pre-swim hygiene regime
  • Continual addition of a flocculant (in my opinion a slow dissolving substance such as Jolly Gel will fulfill this criteria and I believe that poly electrolytes such as this are as certainly as good as aluminium based substances)
  • Inspect the filter interiors annually
  • Get water treatment plants serviced by competent companies to a specification written by a competent person and monitor the work.
  • Sell or give away containment nappies.



If we believe there has been a diarrhea release into the pool.
1. Close pool.
2. Phone me on 07885 615547
3. Advise all bathers to shower thoroughly. Advise them that you have a chemical parameter that you are not entirely satisfied with.
4. Double flocculation rate.
5. Raise chlorine to 30mgl and maintain for 240 minutes (four hours). [WHO recommendation]. There is now a titration tester that will accurately measure this level.
6. Sweep pool repeatedly during this period to ensure circulation is reaching all parts of pool
7. Keep pH in the 7.2 to 7.4 range
8. Stay closed for a day as it is unlikely that you know the true turnover time of the pool.
9. Backwash and re-open

IMPORTANT: Do not backwash until now, because if you backwash earlier you are likely to introduce the oocysts into the bottom of the filter and then back out into the pool when you go back on-line.

I fully appreciate that in these days of high inflation, energy and water costs these sorts of measures could actually close pools but surely this expenditure is preferable to what it cost the Scottish local authority in loss of goodwill, income and predicted compensation costs in excess of £100,000 plus any fine and costs if it now ends in court. But then in a weakly regulated industry there will always be those willing to take a chance. Any opinions expressed in this article are the authors.

Allen J Wilson FISPE MInstSRM is a consultant and lecturer for ‘Studies In Work’ H&S Consultancy specialising in the recreational water industry.


Wilson’s Pool & Spa Plant Operators Handbook. Click below for further info…


Its 7am and your pool is just opening for the day and your staff are experiencing a pool problem ???
If you are having issues, this section will help you.

Consultancy projects

Consultancy projects from Studies In Work are carried out primarily by Allen J Wilson who is Health & Safety and Management qualified.
Read more…

Areas of Specialisation

One of the areas of specialisation is the safe operation of swimming Pool and Spa Plant.

• Lecturers used by Studies In Work are Management & H&S qualified

• Studies In Work are public liability and professional indemnity insured.

• Studies In Work deliver lead body training for ISPE