pH Balance in Drinking Water

pH stands for 'potential hydrogen', which refers to the amount of hydrogen in with the water. The pH scale ranges from 0 – 14, with a pH around 7 considered to be neutral. As the pH decreases below 7, acidity increases, and as the pH rises above 7, so too does the alkalinity. Therefore water that has a pH balance of less than 7 indicates that the water is acidic, and if the pH is higher than 7, it indicates that it is alkaline.

Effects of pH on Human Health

According to the World Health Organization, exposure to extreme pH values (pH <4, or pH >10) results in irritation to the eyes, skin, and mucous membranes, with severity of symptoms becoming more pronounced at the more extreme ends of the pH scale. The pH balance of drinking water is not likely to reach these extreme levels, and consequently it is not considered to pose a direct health risk to humans as drinking water contaminants. pH is listed on the list of secondary drinking water contaminants, with a recommended standard pH of between 6.5 – 8.5 set by the US Environmental Protection Agency (EPA) as a guide for drinking water. Like other aesthetic drinking water contaminants, pH can cause problems that warrant pH levels to be monitored, and maintained within certain boundaries.

Other Problems Associated with pH in Drinking Water

Drinking water with a high pH (high alkalinity) may indicate that the water is hard. Hardness in water can make the lathering of soap difficult, which can cause problems when washing dishes and laundry. Hard water can also lead to a build up of scale deposits in pipes and plumbing fittings, which can reduce water-flow, and reduce the lifespan of certain appliances. Drinking water with a high alkalinity can also taste unpleasant, and give coffee a bitter taste.

Due to its acidic nature, drinking water with a low pH can be highly corrosive, which can lead to leaching of metals such as lead, copper, iron, manganese and zinc, and result in damage to plumbing fittings and piping. The leached metals can give an unpleasant metallic taste, and can stain bathroom and kitchen basins and plumbing, as well as laundry.

Testing Drinking Water pH

pH is typically measured either electronically or visually using one of the following methods:
  1.   Laboratory quality pH meter and electrode
  2. Pocket pH meter with multi-parameter probes
  3. Visual/color analysis using pH strips
While all the above methods can be used to measure pH, the most accurate result is received when tested with high quality laboratory equipment, and this is recommended for drinking water.

Water Purification Solutions to Correct pH in Drinking Water

Home water purification treatment methods to adjust pH balance include neutralizing filters, or neutralizing solutions. A neutralizing filter containing an alkaline filter medium such as ground limestone (calcium carbonate) can be used to increase the pH of acidic water. The filter will require regular backwashing to remove particles that have accumulated on the filter bed, and the neutralizing substrate will need to be replaced from time to time. The calcium carbonate or magnesium used in the neutralizing filter to decrease acidity in this process may be absorbed by the water resulting in increased hardness. This can be corrected by using a water softener, or by filtering out the calcium and magnesium ions.

Another method of purification used to adjust pH levels is the addition of a neutralizing solution, usually soda ash or potassium, which is fed by a chemical feed pump to the water supply to reduce drinking water acidity. If drinking water has a very high pH, and is extremely alkaline, sulphuric acid can be added to the water supply to decrease alkalinity using the same water purification method.


Connecticut Department of Public Health. 'Publication No. 18: pH-Acidity of Private Drinking Wells.' Private Drinking Water in Connecticut. May 2009.

World Health Organization 'pH in Drinking Water.' Background Document for Drinking Water Quality. WHO/SDE/WHO/03.04/12. 2003.

UMass Extension. 'pH-Acidity of Private Drinking Wells.' Healthy Drinking Waters for Massachusetts. 06/01/07.


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