I rode several bikes between 1976 and 2004 on the despatch circuits. Filling up twice a day was normal, and I'd always hit the supermarket pumps if at all possible. NEVER had any issues with loss of power or breakdowns due to water in the fuel.
However, Left over winter, both the Briggs & Stratton mower engine, and the two stroke strimmer developed issues when called upon to restart in the Spring - but only one year. Both suffered from water in the petrol. Flushed out and all OK.
Summary: Ride more often.