Marzipan.

I am suspicious of such numbers. The same amount of water falls on vegetable fields as cattle fields. I see that the numbers for beef are sometimes attributed to 'feedlot' beef. I guess those are 'inside' cows that don't get out and graze in open fields. Also, assuming a regular cow is 1000lb or so, that is 1847 x 1000 = 1,487,000 gallons of water. Multiplied by a reasonable herd size of say 100, = 148,700,000. Yeah that's a 148 million gallons for my guess at a medium herd. So, the numbers don't add up for me.
Am I crazy, are my sums okay?

95 million cows in the US at 1000lb each, times 1847 = 175,465,000,000,000 gallons of water.
Total US usage according to USGS is 322 billion gallons per day, times 365 = 117,530,000,000,000 gallons of water. Therefore, cows use more water than the entire US does, by about 60 trillion gallons per year by my estimate. Clearly, this cannot be so.

Cows weigh in at about 1600 to 2400lbs, and 61% of that is meat, so my 1000lb estimate is close enough for the back of an envelope.

I didn't include billions of chickens, and about 240 million pigs in the calculation, because things were already so far off the rails. Someone is not providing accurate numbers, and they aren't off by a little, they are off by a lot.

"Daily water intake may vary from 3 to 30 gallons per day depending on age, body size (weight), stage of production, and the environment (mainly air temperature).
As a rule of thumb, consumption will range from 1 gallon per 100 pounds of body weight during cold weather to nearly 2 gallons per 100 pounds of body during the hottest weather."

1000lb cow = let's call it 15 gallons per day, times 95 million cows = 1,425,000,000 gallons per day, times 365 = 520,125,000,000 which is an entire order of magnitude lower than the chart estimate. And I've seen estimates as high as 2400 gallons for one pound of beef, and it doesn't add up. 520,125,000,000/95,000,000,000 =5.475 gallons.

The optimum age for cow slaughter is under 36 months, which gives 16.5 gallons per pound of beef. Further water will be used to process, store, transport, etc.

This is crazy off. Another tack: one cows drinks 20 gallons per day for 1000 days = 20,000 gallons, and yields about 1000lbs of beef = 20 gallons per pound.

My conclusion is that people use a lot of insane metrics. So much so that they are off by an entire order of magnitude. And these numbers are everywhere.