A BK17 pilot reversed course and landed safely at his departure airport when the FUEL FILTER warning lights for both engines illuminated in sub zero temperatures. Inspection upon landing discovered water and debris in the filters.

Narrative

While receiving VFR flight following; I observed diminishing ceiling and visibility conditions in our direction of flight. I elected to divert back to my departure airport. Within several seconds of starting a right turn back; I observed the FUEL FILTER I light illuminate. The checklist was pulled and power was reduced in anticipation of a Single Engine Failure. Seven minutes later the FUEL FILTER II warning light illuminated as well.In accordance with the checklist; I prepared for the possibility of a Dual Engine Failure. Given the remote location we were overflying and the below-zero temperatures at the surface; I expressed my choice that the nearest safe landing area would still be back at the departure airport. I continued to monitor engine instruments and the landing was made without any engine anomalies. Upon retarding engines from FLY to Flight Idle; each FUEL FILTER light extinguished. After closing our flight plan the on board Technician contacted his Maintenance Manager. Upon inspection of the fuel filters; water and debris was discovered. The FBO where fuel was most recently purchased was notified of this discovery.