The endurance challenge is due to start with a 1500m open-air swim in Strathclyde Loch in North Lanarkshire, followed by a 40-kilometre cycle and a 10k run on surrounding roads and paths.
However, persistent worries about the quality of the water in the loch are now forcing the organisers to canvas alternatives locations.
As recently as June 23, 80% of the people who took part in an open-air swim at Strathclyde loch fell ill with sickness, stomach cramps and diarrhoea. Some of those affected tested positive for norovirus, also known as the winter vomiting bug.
The loch was closed to all water sports and boating after the outbreak, which was blamed on heavy rains contaminating the water.
Yesterday, after six weeks, it reopened to surface sports such as rowing and kayaking but remains closed to "immersion sports", including swimming, water skiing and windsurfing.
Although no-one was hospitalised, NHS Lanarkshire confirmed 57 out of the 70 swimmers became unwell with gastroenteritis a day or two days after their swim, with symptoms of abdominal cramps, nausea, vomiting and diarrhoea lasting up to 36 hours.
North Lanarkshire Council officials said the water had been "well within acceptable open-water swimming guidelines" on June 11 and June 21, but heavy rain in the 48 hours before the Western Districts Open Water Swimming Championships on June 23 may have led to contamination.
In 2010, Scotland's biggest open-air swim, which attracted 2000 entrants, was cancelled after levels of blue-green algae in Strathclyde Loch were found to be twice the safe level. These can cause abdominal pains, vomiting, diarrhoea, sore throats and blistering skin.
The recurring water problems were discussed by games organisers and the Scottish Government in March, at a meeting of the Glasgow 2014 Strategic Group, it emerged last week.
The group's minutes "noted the risk surrounding the water quality in Strathclyde Park". Although the organisers were trying to improve the situation, "if necessary, contingency arrangements will also be identified", the minutes said.
A second discussion took place at the Strategic Group on June 27, four days after the ill-fated swim at Strathclyde Loch.
Glasgow 2014 officials last night confirmed they were now developing contingency plans, but said no final decisions would be made until after technical advisers reported back in a year's time.
Scottish Water and the Scottish Environment Protection Agency (Sepa) are currently working on a £150,000 project to improve the quality of the loch's water before the Triathlon in July 2014.
John Wilson, the MSP for Central Scotland, said: "Failure to attract the Triathlon would be a major blow to the economic benefits expected for North Lanarkshire."
A Glasgow 2014 spokeswoman said: "We are working in partnership with a number of organisations within a technical advisory group tasked with ensuring the loch in Strathclyde Country Park continues to be used for sporting and recreational purposes and as the Triathlon venue for the 2014 Commonwealth Games.
"As part of this process we are developing contingency plans to mitigate against risks and issues."