6 Sections on Water Alkalinity is all you need to read before drinking it!

Do you know water alkalinity and pH are two different aspects of water? Or do you know that water alkalinity and hardness are generally caused by the same sources but still exhibit different properties? Checkout this improved Urban guide to get all your answers!

What is Water Alkalinity?

Alkalis are bases that are soluble in water. Whereas Water Alkalinity is a measure of the resistance water offers to any change in its pH. It could be defined as the amount of acid that can be added to water for it to neutralize and prevent a change in its pH. It illustrates the buffering capacity of water. A buffer solution works by absorbing the H+ ions released by addition of acid to the solution.

Most commonly found Alkalis in nature are:

  • Bicarbonate
  • Carbonate
  • Hydroxide

The unit it is expressed in is parts per million (or ppm). High ppm suggests the presence of high number of components responsible for alkalinity in water.

Why analyze Alkalinity for Water Quality?

Is Water Hardness and Alkalinity the same thing?

Is Water Hardness and Alkalinity the same thing?
It is true that both of the properties of water have the same sources. Actually when water seeps through rocks, it dissolves up certain minerals like calcium, magnesium. Similarly when Rain falls down it dissolves certain amount of Carbon Dioxide to form a weak Carbonic Acid. This upon coming in contact with say, limestone could result into formation of:

H2CO3 + CaCO3 = HCO3 + HCO3 + Ca2+

Result of the above reaction is formation of Bicarbonates 2(HCO3) and release of Calcium ions (Ca2+).
Bicarbonates results in increase in Alkalinity. Whereas the release of Calcium ions contributes to the hardness of water. So they are not similar thing but by-products of the same reaction.

In fact both are indicative of the presence of each other.

What's the difference between Water pH and Alkalinity?

Water pH

Water Alkalinity

pH just indicates if the water is acidic, neutral or basic

It defines the buffering capacity of water towards acidification.

Represented on a LSI Scale

Represented in ppm (parts per million) or in mg/L

Water pH measures the amount of hydrogen ions (H+) in water

It is the measure of the carbonates, bicarbonates and Hydroxide in water



River flows through many types of rocks and soil. Similarly ponds and lakes are also surrounded by many such geological elements.

Carbonate rich in soil and rocks such as Limestone, Phosphates, Borates, Silicates results in raising the alkalinity of water. They increases the buffering capacity of water.
Whereas Igneous Rocks and Sandstones often have little to no effect on alkalinity of water.



The mines are often rich in many types of minerals due to excavation. These minerals when dissolve in water (rainwater), becomes acidic in nature with pH as low as 2. If allowed to flow to a nearby stream could prove fatal to many aquatic lives.

Metal Construction

The metals are one of the building blocks of human civilization. Corrosion of metal architecture such as bridges, and dumping of waste metals in water could result in water acidification.

Urban Water Alkalinity Standards

United States Environmental Protection agency recommends:

Drinking water pH between 6.5 - 8.5 on a scale ranging from 0 to 14.

The water through our water supply may be high or low in alkalinity. Either of the extremes is non-recommended for human use.

There is no such standard hard and fast rule for alkalinity of water, but we at Urban Aqua Care generally prefer:

80 ppm < Total Alkalinity < 120 ppm.

The standard for the hardness level may differ slightly for different guidelines issued by many organizations but the standards remain more or less the same.



pH Paper

A change in alkalinity cannot be detected visually but only through use of a pH paper.

How to use the pH paper?

Hold the paper from one end and dip the other end of the paper into the sample
A color change is observed
Use a pH scale. Match the color of the pH paper and that of the scale.
The corresponding reading of the color on the scale gives the accurate pH of water. Through this we can determine if the solution is alkaline at all.


Once we have identified that the given water sample is an alkaline through a pH paper. We then use the buffering capacity of water to measure its alkalinity level.

An acid of known pH level and strength is added to a known volume of water sample.
Due to addition of the acid, the carbonate and the bicarbonate in the water sample starts to get used up in order to neutralize the acid.
As soon as the entire bases gets used up, the pH starts to fall linearly.
A change in color is observed.
This linear fall indicates the end of the buffering capacity of the water sample.
The acid used in the above process is known as 'Titrant' and the entire process is known as 'Titration'.

Urban Water Treatment

Muriatic acid

Dilute Muriatic acid added can neutralize the bases in water.

To raise the alkalinity of a water sample

  • Baking soda
  • Aeration

Aeration increases the oxygen level in water. This reduces the level of dissolved Carbon Dioxide and thus carbonic acid. This raises the alkalinity of water. It is always recommended to use natural aeration to prevent over aerating water.

Note: If there is a significantly high or low alkalinity level in water you might want to have a conversation with your local municipality water supplier.



Alkalinity is important for aquatic life because of its buffering capacity. This buffering ability of water protects the living organisms inside it by preventing acidification of water. An Optimum pH range of 6.0 to 9.0 is required for organisms to survive. A stable pH level is required for organisms to thrive.

Check out the causes of Acidification in water.

Plant Growth and Nutrition

Plant irrigation with water of high pH but low alkalinity is not a matter of concern. But water having high pH and high alkalinity can have an adverse effect on the plant growth. This is because it affects the plants ability to extract nutrition from soil and water.

Whereas optimum level of alkalinity is used for irrigation and may provide plants with essential minerals. Certain deficiency caused by the lack of calcium and magnesium ions can be prevented by using alkaline water.


The high alkaline water reduces the effectiveness of pesticides. Certain pesticides in order to work effectively must mix with water to form an acidic solution. A high alkalinity in water thus neutralizes any acid formation thus interfering with its use.

To Drinking Water Source

Alkalinity is also important in considering the treatment of drinking water and wastewater because it influences cleaning processes like anaerobic digestion. When alkalinity level in water is higher than the natural level of alkalinity in the soil, water may be unsuitable for use in irrigation.

Alkalinity is important in the treatment of wastewater and drinking water. It can influence the treatment processes such as anaerobic digestion. Water can also become unsuitable for use in irrigation if it is higher than the natural level of alkalinity in the soil.


Extreme high and low alkalinity are unfit for human use.

  • They can cause a burning sensation in eyes.
  • Itchy skin is another symptom.