Apple Cider Vinegar & Chicken Water (Part 1)

A customer (Scott from Oregon) recently contacted us to ask whether adding apple cider vinegar would clog or damage the metal poultry nipples (valves) on the BriteTap chicken waterer.  

The BriteTap chicken waterer. Chickens drink from poultry nipples
located on the bottom. These valves are made of plastic and steel. 

Scott normally gives his chickens water with 2 tablespoons per gallon ACV in the water. The dilution sounded pretty minimal and our first reaction was that this probably would not be an issue. We told Scott we would look into this further.  

In a series of articles planned for this web site, we'll describe experiments we are conducting to determine a safe and effective dose of ACV that can be used in the poultry nipple watering systems such as the BriteTap chicken waterer.

pH and the Measure of Acidity

In chemistry, pH is a way of measuring the acidity or alkalinity of a particular liquid. The scale is measured in numbers from  0.0 to 14.0.  Highly acidic liquids such as battery acid have a pH of 0.0. Highly alkaline liquids such as Lye have a pH of 14.0.  Pure water has a pH of 7.0. This is right in the center of the scale and so pH 7.0 is often referred to as "pH Neutral." In other words, neither acidic nor alkaline.  

Since we are going to explore acidifying water, we think it's helpful to know the pH of some familiar foods products as a way of gaining some perspective on the subject of pH. To that end, below are pH levels for some common acidic liquids:

• Lemon Juice - pH 2.0
• Coke Classic -pH  2.5
• Pure Vinegar - pH 2.5
• Orange Juice - pH 3.8
• Tomato Juice - pH 4.3
• Milk - pH 6.0
• Pure Water - pH 7.0 (pH neutral)

How We Did the Test

When Scott first asked about adding 2 Tablespoons of Vinegar to a gallon of water it didn't strike us as a high dilution. But there's nothing like doing an actual test to determine the truth.  So that's what we did and what we learned surprised us.

To conduct the test, we purchased Bragg Apple Cider vinegar from our local grocery store. Bragg is an all natural brand that is favored by backyard chicken owners that add vinegar to their chicken's water.  Bragg vinegar is somewhat cloudy because it contains the "mother of vinegar." This is a somewhat slimy substance made up of various strains of bacteria that are cause apple juice to ferment into vinegar.  The "mother" is believed to be particularly healthy and so Bragg is a frequent choice by chicken owners.

To conduct the test, we used a 5 milliliter medicine syringe similar to the one shown below to accurately add the Bragg vinegar to a quart of water.  

Photo by Erich Schulz

We tested each dilution using pH test papers sold by a company called MicroEssentials. When these test papers are dipped in the vinegar and water solution, the color of the paper test strip changes depending on the acidity of the liquid.  You then compare the color of the test strip with the chart on the test paper dispenser and find a color that closely matches the color of the test strip. You then read off the pH.

We purchased test strips that measure pH in half-step increments to get the most accurate reading we could. The below table shows the color for each half step of pH beginning with pH 0 (red) through slightly acidic pH 6.0 (dark green).

Photo by Michael Krahe

Test Results 

Below is a table that shows the results of our test. Specifically, the pH of various dilutions of apple cider vinegar in water. We've calculated the dilution rate in teaspoons per gallon, tablespoons per gallon and milliliters per liter of water to make the math easy for anyone who is interested in planning on adding vinegar to their flock's water supply.

Our customer Scott normally adds 2 Tablespoons of vinegar per gallon of water. As it turns out, this results in a solution that's much more acidic than we would have guessed -- about 3.5. 

Potential Impact On Metal In Poultry Nipple Valves

According to the U.S. Department of Energy Fundamental Handbook Chemistry, the corrosion rate of iron and steel are independent of pH in a range from pH 3.0 to pH 10. In other words, the pH doesn't impact the rate of metal corrosion for a very broad range along the pH scale. 

However, once the pH falls below 3.0, the corrosion rate increases dramatically (see below table). 

A dilution rate of 2 tablespoons vinegar per gallon of water (3.5 pH) is right on the border of being highly corrosive to iron and steel. In theory this is still OK, but theory and practice can be different. In the real world, customers may use vinegar that's more acidic than the batch we tested, or more likely, customers may make measuring errors when adding the vinegar to water that would drive the pH below 3.5.  The resulting mixture might be highly corrosive to the metal in their poultry valve waterers.

As a side note I would mention that the Department of Energy conducted these tests because they wanted to understand the impact of pH on metal used in the construction of nuclear power plants. I have no reason to question the accuracy of their findings.

Current Recommendation

Given what we know right now, ChickenWaterer.com recommends that backyard chicken owners using poultry nipple waterers and adding apple cider vinegar to their flock's water, keep the dilution rate to 1 teaspoon ACV per gallon. That would correspond to a pH of about 5.0 -- well, within the theoretical safe zone and a rate that would allow some measuring sloppiness without consequence.

Next Steps

To validate this recommendation, we plan to place poultry nipples in a various dilutions of vinegar (pH from 3.0 to 7.0) and observe what happens over time.  We'll post the results of this test in a future article.  

We also plan to test the impact of vinegar (acid pH) on micro-organisms that live in water because Chicken owners who use apple cider vinegar often site it's ability to control algae as one of the reasons for adding it to their flock's water supply. Stay tuned....

Posting sponsored by ChickenWaterer.com, makers of the BriteTap automatic poultry waterer. The BriteTap waterer shields water from dirt and poop. The water stays clean and there are no messy pans for you to wash out.