Despite appearances, the federal government knows it wastes a ton of money. 
That's why each agency is equipped with an Inspector General, whose sole job it is to investigate and identify government waste. 
This can take the form of calling out questionable or improper use of funds, finding structural problems, or just pointing out opportunities where Uncle Sam could have saved some money. 
Twice each year, the IGs report back to Congress with details on what they found. 
We went through the most recent edition of these reports to find the most egregious instances of government waste or inefficiencies that the Inspectors General found. 
Several of these — especially ones that involve recurring payments or structural inefficiencies —  haven't been fixed yet.
What we found in the reports could have saved the government a combined total of more than $15.75 billion.