Sanitary workers cleaning septic tanks trapped by methane gas is commonplace in developing countries like India.
It is now catching up in the West too. Fiver persons fell victims to the deadly methane emanating from a manure pit in a dairy farm in Shenandoah Valley, Virginia, US Monday evening.
Scott Showalter, 34, a Mennonite farmer who climbed into the pit to unclog a pipe was the first to be killed by methane. His wife, two young daughters and a farmhand followed in his trail.
Farmers typically take pains to ventilate manure pits where methane often gathers. A family member questioned whether cattle feed could have trickled into the pit and accelerated the formation of the gas.
"You cannot smell it, you cannot see it, but it's an instant kill," explained Dan Brubaker, a family friend who oversaw the construction of the pit decades earlier.
About once a week, waste is pumped from the roughly 9-foot-deep pit into a larger pond. When something clogged the drain, Showalter shimmied through the 4-foot opening into the enclosure, which is similar to an underground tank. He would have climbed down a ladder into about 18 inches of manure.
"It was probably something he had done a hundred times," Sheriff Donald Farley said. "There was gas in there and he immediately succumbed."
Believing Showalter had suffered a heart attack, police said, a farmhand followed him moments later and also passed out.
That's when another farm worker alerted Showalter's wife, Phyillis.
"The family took off to try to get him," said Sonny Layman, who rents a house on the farm. "Phyillis threw the phone out at me and asked me to dial 911." Layman instead followed her and two of the Showalter's four children.
By the time he got to the pit a few feet away, "They were all gone, except Phyillis."
Layman said he tried to pull the woman out of the pit but could not. She died, along with daughters Shayla, 11, and Christina, 9, and farmhand Amous Stoltzfus, 24.
The Showalters' two surviving daughters were being cared for by family members.
On Tuesday, a cousin of Scott Showalter's questioned whether runoff from a pile of brewer's grain had accelerated the formation of the gas. Scott Showalter had been using the grain to feed his cattle.
"It rained, and some of it ran down into this holding pit, it fermented and made a toxic gas," said Bruce Good, who saw Showalter about once a week.
Whether the victims suffocated from the fumes, drowned or died of another cause might never be known. No autopsies were planned, in part because investigators were satisfied that the deaths were accidental, the sheriff's office said.
The deaths struck hard in this picturesque farming region dotted with red barns, gleaming silos and church steeples that peak above rolling fields.
The Showalter clan is well known in the community where neighbors do each other's laundry. On Tuesday, friends tended to the family's animals.
"The cows have to be milked twice a day, even in an ordeal like this," said Frank Showalter, Scott's great uncle, standing a few feet from where his relatives died.
The Showalters milked 103 cows on their farm west of Harrisonburg in Virginia's Shenandoah Valley. They belonged to a conservative Mennonite church whose members shun many of the trappings of modern society but drive cars, use telephones and, according to police, take modern farm-safety precautions.
Fellow church members were in shock Tuesday, said the Rev. Nathan Horst, a Mennonite bishop.
"We've never had a tragedy of this magnitude," he said.
Doug Michael, a childhood friend of Scott's, described him as a dedicated farmer and a family man.
"Scott was a very likable young man, very friendly, always going out of his way to help anyone who needed a hand," Michael said.