Speaking to The Grocer at the UK Soft Drinks Conference in Leeds this week, he said kids tended to use double concentrates in the same way as classic dilutables potentially damaging their health.
"The change to double concentrate is driven by sustainability issues, which is positive," he said. "But at home kids will pour the same amount as before, so consumption is likely to be driven by having stronger product in the glass.
Although most squashes contained sweeteners, kids were probably consuming more than recommended, he said. "Does that increase obesity down the road? I don't know, but it'll keep the sweet tooth in society going."
Bottlegreen's cordials were triple-concentrate but targeted adults, he said, and their syrupy consistency made them difficult to under-dilute.
Britvic which debuted a £4m Robinsons Double Concentrate TV campaign this week showing children testing whether they could get 50 drinks from a single bottle said there was no danger of under-dilution.
The ad made clear kids didn't need to pour as much, and 'use half as much' wording on-pack would help manage squash quantities, it said.
"We know children like to pour their own squash, so Robinsons Double Concentrate comes in an easy-grip bottle and has a unique pour-control feature that helps minimise over-pouring," said brand director Jonathan Gatward.