Carl William Storer, from Tamworth, had visited Chasewater with friends for a day out on June 30.
Police initially believed that Mr Storer had gone into the water to rescue a young girl who had got into difficulty.
But an inquest at Cannock Coroner’s Court on Tuesday was told that that was not the case and that he had been asked by friends to get the children out of the water, and as they left the water he swam past them.
A member of public went in the water to try and rescue Mr Storer, but was unable to reach him.
Emergency services attended shortly after 6pm and Mr Storer was recovered from the water a short time later.
A post-mortem listed a cause of death as drowning.
The coroner warned of the dangers of swimming in lakes and rivers after the inquest heard that warning signs about the dangers of swimming in Chasewater Reservoir.
Detective Sergeant Andy Curran, from Staffordshire Police said: “He [Carl] had been asked by the friend to collect the children, he did that and stayed in the water and got into some difficulty.
“The children were both able swimmers and the water they were in would have only come up to chest height.
"Going from the children’s account, he went into the water to go get them and then swam beyond them.
"He had combat trousers on which, when wet, can become quite heavy.
“The children got out of the water, but Mr Storer did not.
"The daughter said he swam beyond her and that he had been going under the water deliberately.
"He tragically got into difficulty.
“A member of the public went into the water to try rescue him but to no success.
"Emergency services were called and used boats and inflatables and managed to pull him out a few feet away from where he was last seen.”
The hearing heard that there was no alcohol or drugs present in Mr Storer’s body.
Recording a verdict of accidental death, assistant coroner Ian Smith, said: “Sadly it appears all concerned ignored warnings given in and around Chasewater.
"Any open pool of water is going to be cold, even in June.
"People do not seem to appreciate how cold these lakes, pools, canals are and how dangerous they are.
“Carl went into the water to fetch them, not saving their lives, getting them out – he then submitted to the cold and has drowned.”
No family members were present at the hearing in Cannock on Tuesday, but after Mr Storer’s death, in a tribute they said: “You were a really good brother and you will be deeply missed by family and friends.
“Rest in peace and fly with the eagles. You will always be loved.”