Legionnaires' traced to spa pool

Brian Sullivan used to soak in his spa pool after his daily workout to ease aches and pains.

While lying back in a spa is relaxing, making sure the water in the pool is clean can be exhausting. You need to treat the water to keep it free from bugs, as well as check the pH, alkalinity and calcium hardness of the water.

Brian thought he’d found an easy way to keep the water in his spa clean: a product called Simplesilver.

“A single tablet that automatically treats and balances your spa pool water for 12 months,” the Simplesilver website claims.

All was going swimmingly until February 2020, when Brian felt breathless. He went to the doctor and was diagnosed with legionnaires’. He was put on oxygen in the doctor’s surgery while he waited for an ambulance to take him to hospital.

“I was quite surprised it was so serious,” Brian said.

Legionnaires’ disease is caused by breathing in airborne particles carrying legionella bacteria from soil or contaminated water. Last year, 161 cases of legionnaires’ were reported in New Zealand. Six cases were traced to contaminated spa pools.

Jimmy Wong, Canterbury District Health Board health protection officer, had the spa water tested. The lab report confirmed there was legionella bacteria in the spa pool, he said.

Brian bought the Simplesilver he used in his pool from an online retailer. The retailer refunded him $790 for two packs of the product after he told it what had happened.

Product claims

“One step, once a year, for the complete spa pool water treatment.” That’s the claim on Simplesilver’s website.

The homepage also states Simplesilver will keep your pool in “pristine condition – guaranteed” with “no other products required”. You can “set and forget”.

However, Silver (NZ), which distributes Simplesilver, said an “approved filter sanitiser” must be used and the water pump set to circulate water at the required flow rate.

For his part, Brian had been using a filter cleaning fluid though stopped “because it would not rinse clean and built up some foam in the spa”.

“If the recommended and required flow rate of the filter circulation pump is reduced by half, then the Simplesilver product is only 50 percent effective,” Silver (NZ) said.

“In addition to this issue, not cleaning the filters effectively with an approved filter sanitiser will further restrict the water flow, hence further diminishing the correct amount of Simplesilver minerals … These facts are clearly and repeatedly stated and explained on our website,” the company said.

But we think the headline claims for this product – “set and forget”, “maintenance free”, “one step, once a year” – could easily convey a different picture.

The website also states Simplesilver is “certified and proven safe by AsureQuality since 2003”. However, Silver (NZ) declined to provide the AsureQuality report to us unless we agreed to keep information about the product’s ingredients confidential.

AsureQuality said it had asked for the reference to it on Simplesilver’s website to be amended. AsureQuality said it had assessed Simplesilver for use in spa pools, based on information provided by the manufacturer. However, this assessment was not a product endorsement.

The Commerce Commission has received one complaint about Simplesilver.

How effective is silver?

Professor Stuart Khan, a water quality expert at the University of New South Wales, said there’s limited understanding of the range of pathogens silver is effective against.

“Most importantly, there is limited evidence to show [silver] is sufficiently effective to inactivate viruses,” he said.

Silver is a much weaker disinfectant than chlorine – commonly used to treat pool water – “so tends to require high concentrations”.

Unlike chlorine, “there is no simple widely available method to routinely check silver concentrations in a spa”.

The effectiveness of silver is also likely to be significantly affected by water quality variations, Professor Khan said.