When a father of three was sucked into a stormwater drain last week his work colleagues refused to loosen their grip until police told them it was time to let him go.

The colleagues of Paul Smith, 43, kept trying to pull their friend out of the water, long after they realised he had drowned at a Lucas Heights recycling plant in Sydney's south.

Family tragedy: Paul Smith, pictured with his daughter Emma.

His brother Chris Smith said this was a testament to how much he was loved and liked by his work colleagues who were as close as family.

The skies were black and the rain was belting down across Sydney when Paul Smith went to clear a drain that had become blocked with sticks and dirt about 3pm last Monday.