Many have experienced success with water acidification programs that are properly designed to deliver the right pH at the right times.. But given that water acidification doesn’t seem to change the pH in the intestines, how does it work? The answer seems to lie in the difference between the original pattern of gut movement and digestion in birds and the altered pattern on modern commercial diets. There are several areas in a bird’s gut where movement is actually a two-way street. When a bird was eating whole grain and bugs, the meal would go from the proventriculus to the gizzard for grinding. Then the gizzard would send the meal backwards to the proventriculus for another acid bath. This might happen 5 or 6 times until the meal was ground finely enough to move on to the intestines. In a commercial mash or pelleted diet, this back and forth movement between the gizzard and the proventriculus is dramatically reduced so there is very little acid contact time of the meal in the proventriculus. With a diet that includes whole grains this back and forth movement is frequently repeated before the meal is allowed to enter the intestine increasing acid contact time many fold. The most plausible explanation for the efficacy of acidifying water below a pH of 4.0 in improving performance and in impacting Salmonella and necrotic enteritis is that by acidifying the ingesta in the crop, that low-pH contact time lost to impaired gizzard reflux is being compensated for.