Asg15 gunner here...G models rule

There is a water tank in the aircraft - the water doesn't last long, it's only used for take-off - in basic terms - water was injected into the combustion chamber, increase in oxygen - increases thrust

B-52Gs had a 1200gal water/methanol tank. KC-135A had a 600gal. tank. Electric pumps injected water into usually either the compressor inlet or the diffuser just before the combustion chamber. This increased the mass being ejected from the rear of the engine, thus improving thrust, and simultaneously cooled the turbines allowing for higher RPM operation without overheating. The drawback of the system is that it had the effect of somewhat extinguishing the flame in the combustion chamber, leading to unburnt fuel being expelled aft out of the rear of the engine, thus creating the characteristic black smoke trails. Water injection also greatly increased the noise emitted. The TF33 turbofan version on B-52H and KC-135E was a vastly more efficient powerplant, more thrust, less fuel consumption and no need to use clumsy and inefficient (and heavy) water injection.