This treatment method is used if water is acidic (low pH). Soda ash (sodium carbonate) and sodium hydroxide raise the pH of water to near neutral when injected into a water system. Unlike neutralizing filters, they do not cause hardness problems in treated water.
Injection systems are a point-of-entry system. A corrosion-resistant chemical feed pump injects soda ash or sodium hydroxide solution into the water to raise the pH. The solution should be fed directly into the well to protect the well casing and pump from corrosion.
If the water needs to be disinfected as well as neutralized, dual treatment is possible within the injection system by adding a chlorine solution (sodium hypochlorite) along with the neutralizing chemical.
As with all chemical feed systems, the chemical feed pump must be maintained and the chemical storage tanks refilled. Soda ash, the preferred chemical, is safer to handle than sodium hydroxide. Screens and filters should be periodically checked and cleaned.
Use caution if using sodium hydroxide. If adding it manually, maintain good ventilation to avoid breathing vapors. Add the chemical slowly to the water and ensure complete mixing. Be sure to wear protective gloves, goggles and clothing to avoid skin and eye contact with the chemical. Store sodium hydroxide in a cool, dry place away from flammable materials.
Individuals on a low sodium diet should consult a doctor before installing an injection system. Use manufacturer specifications to compare sodium levels in the treated water to levels consumed from other sources in the diet. Potassium hydroxide may be used as a substitute for sodium hydroxide but may cost more.
Acid injection treats water with a high pH by lowering the pH of water to around 7, which eliminates the soda taste and can improve the effectiveness of chlorination. This method also reduces the potential of pipe corrosion as water with a pH above 9 can corrode metals such as brass, copper, zinc, aluminum and iron.
Acid injection is a point-of-entry system. A chemical feed pump made from corrosion-resistant materials injects a solution of acetic acid (white vinegar) into high pH water. Citric acid and alum can be used instead, although they are more expensive. Weak solutions of hydrochloric acid or sulfuric acid also lower pH but these are more hazardous and require special handling. They are recommended, however, if the pH of untreated water is 11 or higher. After adding the acid solution, the feed rate should be adjusted until tap water reaches a pH around 7.
Chemicals used in acid injection systems should be handled carefully and stored in clearly marked containers, out of the reach of children. When diluting acid solutions it is important to always add acid to water slowly, never add water to acid. Be sure to thoroughly examine manufacturers’ recommendations before purchasing an acid injection system or necessary chemicals.