Keeping the tanks clean from the factory is not enough.
Humorous anecdote - an airplane was being refueled. Got all done and time to unlatch the hose. The handle on the hose shut-off valve would not return to the shut-off position. Because of a mechanical interlock to keep the fuel from pouring out of the hose when it was not coupled to a supply tank or an aircraft, the hose could not be uncoupled without first closing the valve, which could not be done.
Break out the metal cutting saw to slice through the valve, but not before the panicked ground crew tried to pry the hose end from the aircraft, damaging the aircraft severely.
For some reason, known to no one, a meter stick had made its way into that valve when it had been opened, blocking the valve from closing again. Apparently, at some time, the meter stick had been stowed into the hose.
So, on the contract I was working, the requirement was to use fuel connectors that had integral fuel strainers.