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pH - Acidity of Drinking Water

Information on related products can be found on the following pages:
pH Neutralizing Filter Systems
Corrosion in Potable Water

The Secondary Maximum Contaminant Level (SMCL) for pH is 6.5 to 8.5 on pH scale as established by the EPA.

What is pH?

pH is an indicator of the acid or alkaline condition of water. The pH scale ranges from 0-14; 7 indicates the theoretical neutral point. Water with a pH value less than 7 indicates acidity and tends to be corrosive, while water with a value greater than 7 indicates alkalinity and tends to affect the taste of the water.

Acidity or low pH of drinking water is usually a result of natural geological conditions at the site, possibly compounded by acid rain. Testing for the pH of your well water is crucial for:

  • Evaluating the potential for your household plumbing to be subject to aggressive corrosion.
  • Evaluating the potential for your drinking water to contain leached metals such as copper, lead, iron, cadmium, and zinc from your well pump and plumbing system.
  • Determining the effects of proper home treatment on other drinking water contaminants. Depending on the pH level (how acidic or alkaline), pre-treatment may be needed to adjust the pH of your water to a more neutral range.

Otherwise, home treatment systems may not work as designed. Home treatment methods to adjust pH include Neutralizing Filters and neutralizing solutions (soda ash).

Potential Health Effects

The pH of drinking water is not a health concern, however, acidic water (low pH) can leach metals from plumbing systems, which can cause health problems.

Indications of Low pH

Symptoms of low pH are bluish green stains on fixtures with copper plumbing; reddish stains with galvanized iron plumbing; and water system corrosion problems and plumbing leaks.

Testing for pH in Private Drinking Water Wells

To determine the pH, arrange to test your drinking water at a certified laboratory. Follow laboratory instructions carefully to avoid contamination and to obtain a good sample. Home test kits may not provide accurate results. Determining pH is often essential in evaluating the presence and effective treatment of other drinking water contaminants.

Corrective Actions

Neutralizing Filter
If your water is acidic (low pH), you can use a neutralizing filter containing calcite or ground limestone (calcium carbonate) or magnesia (magnesium oxide) to raise the pH. Neutralizing filters must be backwashed periodically since they serve as mechanical filters to remove solid particles from the water. They also require periodic replenishment of the neutralizing material within the filter bed. When acidic water is treated with a neutralizing filter such as ground limestone (calcium carbonate), hardness is added to the water. This happens as a result of adding calcium and magnesium minerals, which the water absorbs when passing through the filter. This is also why the neutralizing materials need periodic replenishment. Installing a cartridge filter prior to the neutralizing filter will remove solid particles from the water and can help to prolong the life of the neutralizing filter.

Arrange to test your water for hardness after installation of a neutralizing filter. Levels up to about 120 milligrams per liter of calcium and magnesium are acceptable, however, at levels between 120 milligrams per liter and 180 milligrams per liter, the user may prefer to soften the water, or remove some of the calcium and magnesium. If either calcium or magnesium is present in your water in substantial amounts, the water is said to be “hard,” because making a lather or suds for washing is “hard” (difficult) to do. Thus cleaning with hard water is difficult. Water containing little calcium or magnesium is called “soft” water. Ion exchange treatment can be used to treat “hard” water. It is also commonly used to remove iron and manganese.

Neutralizing Solutions
For high yield water supplies, an alternate method of neutralizing acidic water is to feed a solution of soda ash to the water supply with a chemical feed pump. Sodium carbonate can raise the pH level to 8 or higher. Where water contains a lot of iron, or if you need to disinfect the water, a chemical feed pump is often used since hypochlorite bleach and soda ash may be mixed in a single solution and fed into the water system with the same pump unit. Potassium can be substituted for sodium if needed. Like sodium, the potassium substitute should be evaluated for any possible human health effects. Too much potassium can cause nausea, diarrhea, muscle weakness, and even cardiac arrest.

See Neutralizing Filter here


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