Not sure here of units used but!!
1 ppm=1/1 000 000
79 000/1 000 000 gives alot less than 79kg!!
Yes, that is why I wrote 79g NOT 79kg as you did.
So once again, for clarity, 1 ppm of water in 79,000 kilograms (kg) of fuel = 79 grams (g) of water (w/w)