How to Adjust Water pH

Last Updated: March 21, 2023 References

pH measures the amount of acidity or base in a liquid. If you need to adjust the pH level of your water—whether for a science experiment, gardening, drinking water, a fish tank, or any other need—begin by measuring the pH level. If you need to decrease the acidity of water, add a basic substance like baking soda. In order to raise the acidity of water, add an acidic substance like lemon juice.^{[1]
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Method 1

Method 1 of 3:

Adjusting pH for Fish, Plants, Pools, and Drinking

1
Treat your drinking water if it’s acidic or basic. The water that you drink should be neutral, with a pH value at (or very close to) 7. If you’ve tested the pH of your drinking water and found that it’s acidic or basic, make adjustments to balance the water’s pH. If the drinking water is acidic (low pH number), add pH drops or tablets to neutralize the acid. Alternately, if your drinking water is basic (high pH number), add a few drops of lemon juice, which is naturally acidic.^{[2]
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- If you’d like the pH level to be permanently adjusted, you can have a permanent water filtration system installed. If your water is basic, install a neutralizing filter or a soda ash/sodium hydroxide injection system.^{[3]
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- If your water is acidic, professionals from a local home-supply store can install an acid-injection system to your house’s water supply.
2
Change the pH of tap water for your houseplants or garden. Most houseplants thrive when given slightly acidic water, between 5.5 and 6.5. If you’ve measured your tap water and found that it’s basic (or too acidic), you’ll need to adjust the water’s pH level before watering your plants. Lime or wood ash can be added to a 1 gallon (3.8 L) container of water to raise the pH. To lower the pH, add phosphoric acid or a tablet designed to lower water pH.^{[4]
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- If you’re unsure about the ideal pH level for the specific type of plant you’re watering, check online or at a local plant nursery. Some plants are very pH sensitive and need water at an exact pH level. For example, onions thrive when given more basic water at a pH of 6.5-7.0.^{[5]
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- Consult your local plant nursery to determine the exact amount of pH-altering substances to add. You can also buy lime, wood, ash, and phosphoric acid or other pH-lowering substances at the nursery.
- If you repeatedly water plants with water outside of the 5.5–6.5 range, they will begin to wither and die.
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3
Add peat to your fish tank to adjust the pH. Fish are very sensitive to the pH in their water and can die if the water becomes too acidic or too basic. Most species of fish thrive in relatively neutral water, close to 7 on the pH scale. If the water has become too basic, add peat moss to lower the pH. If the water is too acidic, add 1 teaspoon (4.9 mL) of baking soda per every 5 gallons (19 L) of water to raise the pH.^{[6]
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- Look online or visit a local pet store to find out the specific water-level pH needs of the breeds of fish you have. For example, if you’re keeping koi fish, they prefer basic water with a pH range between 7.5 and 8.2.^{[7]
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- You can purchase clumps of peat at your local pet store. Put 1 clump of peat into a mesh bag, and place this inside of your fish tank’s water filter. The peat will lower the acid level over time.
- Rapid changes in pH can have a harmful effect on your fish. Remove the fish from your tank before adjusting the pH.
- Test the pH level in your fish tank both before and after making an adjustment. Also test pH before and after altering pH levels in pools or drinking water, as per the relevant section of this article.
4
Adjust the pH in your pool. Swimming pools should be maintained at a slightly basic pH, between 7.2 and 7.8. The pH in pools tends to rise on its own, so you’ll likely need to lower the pool pH from time to time. Pool manufacturers make chemical substances for this purpose. The 2 most common are sodium bisulfate and muriatic acid. Either substance should be added directly to the pool water.^{[8]
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- For more detailed instructions on raising or lowering the pH level in your pool, consult the manufacturer’s recommendations for your specific model.
- You can purchase sodium bisulfate (also called “dry acid”) or muriatic acid at any pool supply store.

Method 2

Method 2 of 3:

Doing Water pH Experiments at Home

1
Add 1 teaspoon (4.9 mL) of baking soda to an 8 oz (230 g) glass of water. Baking soda is basic, with a pH value of 9. Drop 1 teaspoon (4.9 mL) of it into a glass of water, and then stir briskly with a spoon or whisk. Keep stirring until all of the crumbs of baking soda have dissolved.^{[9]
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Research source} Then, measure the water’s pH again using a litmus strip.
- If you started with neutral water (pH 7), the water’s pH should have increased up to about 8.
2
Add 1 teaspoon (4.9 mL) of lemon juice to a glass of water. Mix the 2 liquids together using a spoon. Then dip a strip of litmus paper into the water. Wait a few seconds, and note how the pH level of the water has changed.
- Since lemon juice is acidic, with a pH value of 2, the pH level of a neutral glass of water should have lowered to a 6 or 5.^{[10]
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3
Experiment with various other basic and acidic materials. Many common liquids and dissolvable substances found around the home will alter the pH level of water. Dissolve or mix a small amount of one substance at a time into a glass of clean water, and then test with a litmus strip. If you’re performing a science experiment, make a chart on which you can record the pH values of water with different substances added, each to a separate glass of water. Try adding:
- Coke.
- Red wine.
- Milk.
- Liquid soap or shampoo.

Method 3

Method 3 of 3:

Measuring Water pH with Test Strips

1
Purchase pH testing strips. pH testing strips—also called litmus strips—are thin, small sheets of paper, each about 2 inches (5.1 cm) long by ¹⁄₂ inch (1.3 cm) wide. They are coated with a chemical solution which changes color when exposed to basic or acidic substances. pH strips can be purchased at most health-food stores or at any science supply store.^{[11]
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- You can also purchase pH strips at major online retailers, or at most pet-supply stores.
2
Dip 1 pH strip in a sample of water for 10 seconds. Place about 1 inch (2.5 cm) of the pH strip into water. Dip either side; the entire strip is pH sensitive. Be sure to keep a firm hold on one end of the strip, though, so that it doesn’t slip into the water you’re planning to measure.
- For example, draw a glass of water from your tap if you’re trying to ascertain the pH of the drinking water.
- Or, if you’re trying to adjust the pH level in a fish tank, dip a strip into the water at the top of the tank.
- Alternately, you can use a water dropper to place 1 or 2 drops of water directly onto the center of the litmus strip.^{[12]
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3
Observe what color the pH strip turns. Once the pH strip has been submerged for at least 10 seconds, pull it out and look at the end. The pH strip will have changed color to indicate the presence of base or acid in the water.^{[13]
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- If the color of the strip doesn’t change immediately, wait a few seconds.
4
Compare the pH strip to a pH color indicator. Your pH testing kit should have come with a color chart. The chart indicates the color that litmus paper will turn when exposed to a basic or acidic substance. Match the color of the pH strip to a color on the chart, and you’ll have a good idea of the water’s pH.^{[14]
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- In broad terms, a red litmus strip indicates highly acidic water, yellow indicates mildly acidic, green indicates mildly basic, and purple indicates highly basic.
5
Gauge pH levels using a digital probe reader for more accurate data. Litmus strips are a quick and effective gauge of pH levels, but are not the most precise method of measurement. A digital probe reader (often called a “pH meter”) is a much more accurate device. Unlike test strips, it will determine the pH of a liquid to 2 decimal places. To use the pH meter, submerge the tip of the instrument in water until the display shows the pH reading.^{[15]
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- pH meters are commonly used in science labs and can be purchased or rented through science-supply stores.
- The pH meter may need to be re-calibrated between each usage. Follow the printed directions included with the meter for best results.

Things You’ll Need

Litmus strips
Water dropper
Baking soda
Lemon juice
Clean drinking glasses

Warnings

Take precautions if you’re experimenting with different acidic and basic substances. Protect your eyes with safety goggles, and wear rubber or latex gloves to cover your hands. Some substances, like hydrochloric acid (pH 1) or sodium hydroxide (pH 14) are caustic and can burn your skin or eyes.

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