Why Is pH in Public Water Higher During Summer?

The pH level of water is a vital factor in measuring how healthy a body of water is and how well it can sustain life. The pH level of surface water can vary according to environmental conditions such as seasonal changes. Since public water is often reliant on surface water sources and filtering only removes certain chemicals and organisms, changes in surface water pH can carry into the public water system. The pH of public water is generally higher in summer months because the pH of surface water is higher.

Water pH

• The pH level in water reveals how acidic or alkaline water is and is also a measurement of the concentration of hydrogen ions the water contains. A lower pH, from 1 to 6.5, means the water is acidic, or has a higher concentration of hydrogen ions. A higher pH, from 7.5 to 14, is alkaline, or has a lower concentration of hydrogen ions. The pH level of water is important because most aquatic plants and animals need to live in a particular pH range in order to thrive. Changing the pH from a neutral pH of around 7, which is ideal for most freshwater ecosystems, to either more acidic or alkaline pH can disrupt an ecosystem and cause harm.

Sunlight

• Most ecosystems are set up to maintain a certain pH level naturally, so slight natural variations can be tolerated. In summer there is more sunlight, which boosts the photosynthetic activity of microorganisms, algae, and plants in the water, causing them to use up the dissolved carbon dioxide (CO2) in the water. Since the carbon dioxide in water (H2O) has already mixed with the atoms in water to form natural carbonic acid (H2CO3), the acids in the water are reduced. This reduction of acid raises the water's pH.

Heat

• Higher summer water temperatures exacerbate the problem because higher temperatures increase the rate of natural oxygen loss from the water, which encourages the growth of algae, which in turn increases the amount of carbon dioxide consumed and raises the pH level. All of this occurs within natural tolerances if left on its own.

Fertilizers

• Humans increase this pH swing even more with the introduction of chemical pollution like fertilizers, which are used most frequently during summer months and are present in stormwater runoff in higher concentrations during that time. The phosphates and nitrogen in these fertilizers create excessive algae growth, raising the water pH.

Effect on Humans

• The effect of a slight increase in the pH of water in summer months has more of impact on aquatic life than it does on humans. Humans have a wider range of what our bodies find tolerable. For example, the acid in an orange juice or a pickle come in around a 4 and egg whites come in at 8. The pH would have to change a great deal in order for public water to become unsafe for us to drink and at that point would be adjusted by the municipalities through the addition of acidic substances.