Residential and Commercial fuel tanks for generators or emergency backup power plants can be forgotten about until they are desperately needed. Here in Florida, hurricane season can leave residents and businesses without electricity for weeks. When diesel tanks sit for years, moisture and bio growth build up in tanks leaving generators useless.   Fuel tanks need to be serviced just like the power plants they are supporting.   Florida requires a letter of maintenance for generators providing backup power to hospitals, ALF’s, secured facilities and various other essential structures.  The same goes for the fuel tanks in support. In the event a generator failure occurs resulting in loss of life or secured coverage, the first thing an attorney will ask for is a letter of maintenance.