In some cases, fuel additives that pull water up into the fuel by the means of an emulsifier can be an appropriate response to preventing microbial growth.
The additives address the problem at its source.
Without water, microbes cannot proliferate in the fuel.
By pulling the water into the fuel, it will eventually vaporize in the engine and exit out the exhaust.
In cases involving a Tier-4 engine, water emulsifiers will only create more problems.
Tier 4 engines feed fuel into the combustion chamber at extremely high pressures with very little tolerance for fuel contaminants.