Cher Loh from the Good Housekeeping Institute Cookery School has discovered that stale bread can be revived with just water.
His method involves soaking an unsliced loaf in water before popping it in the oven. He claims that this not only rehydrates the bread, it will actually last longer.
"Then stick it in the oven at 200°C (180°C fan) for a few minutes, and your bread will miraculously be edible once more."
Just be sure that you use unsliced bread, and don’t try this hack more than once on the one loaf of bread.