The survey found that 44 percent of the country's men were at risk of ED, said Pharma Dynamics, a generics pharmaceutical firm specialising in men's sexual health.
Clinical studies suggested that three or more standard alcoholic drinks per week significantly impaired erectile function and sexual satisfaction.
"A sobering thought, since more than 31 percent of South African males already consume over and above five standard glasses of alcohol per week and 13 percent toss back at least three glasses a week on a regular basis."
Over 500 men between the ages of 18 and 55 participated in the national survey, conducted during June and July this year.
According to the World Health Organisation's latest report on alcohol and health, South Africa had the highest alcohol consumption rate in Africa.
Pharma Dynamics spokesman Tumi Motsei said this did not mean men had to cut back completely, but it was important to remember sex and alcohol was a delicate balancing act.
"Men who are under the influence of alcohol may feel more sexual, more willing, and have a stronger desire to seek out a sexual experience, but alcohol actually hampers your sexual performance.
"The liver can only break down the amount of alcohol in about one standard size drink an hour, so regularly drinking more than that means that toxins from alcohol can build up in your body and affect your organs, including those involved in sex," he said.
Men who were dependent on alcohol had a 60 to 70 percent chance of suffering sexual problems.
According to the survey four in every 10 South African men -- young and old -- were currently affected by ED.
Men with ED were twice as likely to have a heart attack, 10 percent more likely to have a stroke, and 20 percent more likely to be admitted to hospital for heart failure.
"In fact, impotence is an early warning sign that cardiovascular disease (CVD) may be looming.
"ED caused by narrowed arteries commonly develops years before any symptoms or problems of CVD, hypertension or diabetes become apparent," Motsei said.