FAIRFIELD — Half-marathon runners typically don’t shower until they’re back home after a grueling 13.1 miles.

This Sunday, however, Fairfield firefighters will douse half-marathon contestants — and members of the public lucky to make it — in water in an attempt to break a Guinness World Record for the most amount of people showering together.

“I think we’re pretty well prepared,” Steve Lobdell, race director of the Fairfield Half Marathon and retired fire captain, said. “We actually placed a limit of 600 people because the numbers keep coming in so strongly.”

The Faxon Law Fairfield Road Races are in their 39th edition and the half-marathon is limited to 4,000 entrants.

According to Guinness World Records, the current record for most people showering simultaneously in a single venue belongs, not coincidentally, to the soap brand Irish Spring. A total of 396 people showered together at the Firefly Music Festival in Dover, Del. last summer.

In earlier reporting, a Guinness World record representative confirmed that the Irish Spring record still stands.

The same representative said that there must be enough showers to cover all participants at the same time, participants must move freely in order to get wet and also must use shower gel or soap.

“I currently have 600 bars of soap in my living room,” Lobdell said with a laugh. “We also have commemorative beach towels for the event.”

The Fairfield Half Marathon is looking to break the record with almost double the amount of people showering together in what will be a “first come, first serve” basis though 90 percent of participants are expected to be half-marathon runners.

“We have 4,000 square feet based on how much room per person needs to shower, firefighters are coming in with a tanker from Weston with 2,500 gallons of water and Fairfield with a pumper and ladder truck,” Lobdell said. “(Guinness World Records) are pretty technical.”

The shower begins at 11:00 sharp.

Runners will go through the finish line in the parking lot, get refreshments and after they’re done, go to an area where they will be divvied up in groups of 50.

“We want to get in as many people as we can,” Lobdell said. “It’ll be a lot of fun.”