This isn't easy unless you know what is raising the pH of your water. Buy a bunch of litmus paper, and start adding acid to a gallon of water with an eyedropper.

Note: The acids usually used for neutralizing alkalie water are Nitric, Sulfuric, and Phosphoric, as they are also fertilizers. However, muriatic (hydrocloric) acid is the least dangerous of the stong acids to use.

Concentrated acids are dangerous to work with. Dishwashing gloves don't hack it with nitric or sulphuric acid. Use nitrile gloves(I think...) or look for acid resistant gloves. Your local farm store should have them. Stores that have safety equipment will also have them. Wear eye protection. Full face mask recommended. Keep a box of baking soda at hand, so that you can neutralize a spill quickly.

It's a good idea to cut strong acids 10:1 with water, adn use the diluted form (still quite strong) as your working solution.

Do a search for safe handling acids on the internet.

Acid added to water will probably just leach right through. Add sulfur to the soil to reduce acidity. But I think trying to bring 9.3 low enough for blueberries is pretty much hopeless.

If your blueberry patch is not too big, try using soda water blended into the tap water to lower the pH.
Buy pH paper to check the pH of the blend.
It might be economically inviable but it is safe.
Use the pH paper on wetted down soil to check how much your tap water actually affects the soil.
You could also think of using gravity fed micro-drippers which have a discharge rate per hour of less than a liter.
This type of irrigation allows the use of water with higher salt content(alkaline), as the salts get pushed to the fringes of the wetted area, without affecting the plants.