Tap water should not be too acidic or basic. It usually measures around a 7, or neutral, on the pH scale of 0 to 14. Neutral tap water typically has a better flavor and keeps your indoor plumbing running smoothly. If you have an especially acidic or alkaline water supply, a filter or water injector can help balance tap water pH.
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Impact of pH Imbalance
Water with a slightly acidic pH level of less than 6.5 may contain elevated levels of iron, manganese and other toxic metals. It's considered "soft" water and could break down metal piping -- leaching metals from the pipes into your water supply. Acidic water also has an unpleasantly sour or metallic taste and may leave bluish stains on your sinks and laundry. Overly alkaline water, which measures greater than an 8, can taste bitter, like flat club soda, and also corrode piping. It's not unsafe to drink this "hard" tap water, but it can form deposits on dishes and make it hard to lather soap when washing.
Why pH Varies
The pH level of your tap water is largely affected by the source of the drinking water and the type of minerals found locally in rock. Pollution and acid rain can also affect tap water pH. Measure your water's pH using litmus paper -- just drop a bit of water onto it and watch the color change to indicate the pH value. Drinking water is normally between 6 and 8.5 on the pH scale.
Neutralize tap water at its point of entry into your home. A neutralizing filter balances your tap water by moving the water through a system and passing it through a filter containing a neutralizing substance. When the pH is greater than 6, calcium carbonate is used to treat the water and bring it up closer to 7. Synthetic magnesium oxide neutralizes water with a pH lower than 6.
An alternative to a neutralizing filter, which requires maintenance and risks overhardening your water, is soda ash or acid injections. Soda ash, also known as sodium carbonate, raises the pH levels of overly acidic water when added to a water system. Install a home system for injection that neutralizes the tap water at the point of entry. Note that people on low-sodium diets should be wary of using sodium carbonate for neutralization and need to consult a doctor before installing. For overly hard, or alkaline, water, use an acid injection system. Acetic acid, found in vinegar, citric acid or alum, are used to bring the pH value closer to 7. Injection systems need regular maintenance and replacement of the chemicals, which may require special handling.