St Mary's residents used up to 22% less water this summer than last.
The Council described the community's efforts during the water shortage as "impressive".
The biggest reduction was in the peak season month of August, with usage across the month between 14 and 22% less than the same period in 2017.
Cllr Steve Sims, Lead Member for Place, said: "I'm absolutely delighted with the efforts locals and visitors have made to save water. We've changed the way the statistics have been presented because at this time of year, just putting a comparison with the previous week doesn't mean a great deal because obviously visitor numbers are going down. Comparing it to last year is much more useful.
"It's incredible to think we managed to save 22% right in the middle of August at the very peak of the season and the figures are still going down. It's important that people keep trying to save water as every litre of water saved now is a litre we have available next year.
"The heavy rain we had last weekend all helps but it won't get into the water table for quite a long while yet so with water levels critical in August, they're still critical now so it's very important to keep up the good work. A big thank you again to everyone."
New water savings devices are available for free from the Customer Hubs at the Library and Carn Gwaval Wellbeing Centre.