How to Adjust the pH of Water With Vinegar

Maintaining or changing the acidic/alkaline balance of water is a major concern for those involved in agriculture, environmental protection or public water supply. On a smaller scale, this balance (called pH) can affect the success of hydroponic gardening, aquarium maintenance, and household cleaning.

One way to change pH is to add acid or alkaline substances to the water needed for a project. Adding vinegar will increase the ratio of acid to alkaline content, although establishing the precise amounts needed may prove difficult. Learn the pros and cons of adding vinegar to water in order to acidify it.

Common white household vinegar

Measuring cup or dropper

Water for project

Water-pH testing strips

Paper and pencil for recording information

Test the water to be used with a pH test strip, to determine the basic acid-alkaline balance.

Add a very small amount of vinegar to a small amount of water. Test the change in pH. PH strips consistently reflect the balance between acid and alkaline components of a solution but do not provide equally accurate information on the exact amounts of those components.

Extrapolate, as best possible, the amount of vinegar you will need to produce the same pH change in the complete water supply. Measure and add vinegar gradually, testing at intervals so that you do not add too much. The pH scale runs from 1 (strongly acidic) to 14 (strongly alkaline) and numbers on the scale progress logarithmically; this is, a pH of 5 is 10 times more acid than a pH of 6, and a pH of 4 would therefore by 100 times more acid than a pH of 6.

Use water promptly or test periodically as the project progresses. Homemakers who report how rapidly the smell of vinegar used for cleaning dissipates see this as a virtue. The mild volatility of vinegar that produces this dissipation, however, serves as a reminder that the acidification produced by vinegar is not stable in solution on a long-term basis.

Repeat testing before adding more vinegar. Add additional vinegar slowly.

For long-term or larger-scale projects, you may wish to explore the varying strengths of vinegar made for commercial purposes. Solutions up to 20 percent acidity take less storage space and may be more economical for big projects.

If changing the acid-alkaline balance of water does not produce the results you need, consider diluting the water for your project with distilled (neutral) water or near-neutral rainwater. Poor results may be related to too-high a concentration of both acids and alkalis, and what you may need is a less potent water supply.