A Cryptosporidium outbreak that resulted in 120,000 people being forced to boil their water for five months cost €19m, a new study shows.
The 2007 outbreak in Galway cost each household €95 and resulted in one in eight hotel and guesthouse bookings being cancelled.
One in five people in the city refuse to drink the tap water today due to concerns about its safety, the study says.
It found that had the water supply to the city and surrounding areas been subjected to an adequate treatment process costing just €1.6m, it would have resulted in an €11 saving for every €1 invested.
The 'Economic Assessment of the Waterborne Outbreak of Cryptosporidium Hominis in Galway 2007' study, which was funded by the Environmental Protection Agency (EPA), says the outbreak lasted for 158 days and resulted in 242 confirmed cases of cryptosporidiosis, "although it was likely the actual number affected was far higher".
Cryptosporidium is a parasite that lives in the intestinal tract of infected humans and animals. It is shed in faeces, and contaminates water and soils.
Infection results in diarrhoea, stomach cramps, vomiting and fever. It can be fatal for those with compromised immune systems. The city's supply became infected by human and animal waste in March 2007, and the outbreak lasted until the following August. The report found:
Cryptosporidium remains a problem across the country, with the latest data showing that 17 water supplies require upgrades to remove the threat.
The report, compiled by researchers at NUI Galway with an official from the HSE, found that households bore costs totalling €3.9m, the hospitality sector another €8m, while the local authorities spent almost €6m.
This includes €388,000 to cover the costs of installing a treatment process to remove the dangerous bug from water.
When the capital investment needed to install the treatment was taken into account, the total cost of making the water safe was €1.6m.