In this era of good clean fuel being available for most of us, mentioned above and worth repeating IMHO are two things.
First, buy your fuel at a known brand high turnover location. Second, check that the dock fuel pumps have in line fuel filters. These are not in lieu of a good on board fuel filter setup.
Fortunately on our DeFever one of the smaller tanks (80g) is continually being filtered from a bottom sump draw feeding the fuel delivery pump to the diesel heater. That tank, one of four, is our ultimate backup. The filter and bowl on that specific Racor have never shown water or debris. Knock on wood.