Having extolled the virtues of alkaline water over our past few articles, let’s go deeper into the chemistry behind the synthesis of alkaline water. Just what is alkaline water in scientific terms and what chemical reactions produce it? That depends on the type of alkaline water at hand.
Alkaline and Acidic
To understand how alkaline water is produced, let’s have a look at the scientific understanding of the alkaline and acidic descriptors. The alkalinity or acidity of a substance is measured based on its pH on a scale from 0 to 14, which itself measures the concentration of hydrogen ions (H+) and hydroxyl ions (OH-).
This pH scale shows where common substances rank based on their acidity or alkalinity. (Image © WikiCommons)
At a neutral pH of 7, the concentrations of both ions are equal. Below a pH of 7, the concentration of H+ is higher and the substance is acidic. Above a pH of 7, the concentration of OH- is higher and the substance is alkaline. Alkaline water typically has a pH of between 8 and 9.
Types of Water Alkalisation Processes
There are two types of processes commonly used in consumer products like water dispensers.
Alkaline Water Filter
While this filter does physically remove particles over 5µm in size, its primary purpose is the treatment of water through a straightforward and reliable chemical reaction. The filter contains a reducing agent, commonly a finely-ground magnesium powder, that reacts with water to produce H+ ions. With a fixed water source and flow rate, the water produced is mildly alkaline with a fixed pH.
Despite having a name right out of a sci-fi movie, a water ioniser is simply a device that uses electrolysis to separate water into H+ and OH- ions. Electrolysis is a very common industrial process used in applications such as water purification, through which fresh water is produced from polluted water, or electroplating to produce chrome-plated accessories. While the exact process may differ between appliance models, producing alkaline water through electrolysis generally aims to leave you with water that has a higher concentration of OH- ions than the source water.
What’s The Difference?
If these two processes were chairs, the alkaline water filter would be a sturdy and well-crafted oak chair, while the water ioniser would be a high-tech office chair with lumbar support and a dozen adjustable parts.
What the alkaline water filter lacks in sophistication, it makes up for in rugged reliability and ease of use. With no electronic components or complex moving parts, there are far fewer points of failure than in a water ioniser. And in the rare event that the filter malfunctions, a replacement is simple and economical. In contrast, a malfunction in a high-tech water ioniser would be nigh impossible for the average person to diagnose and fix, and could call for a potentially costly repair depending on your warranty’s terms and conditions.
The alkaline water filter is also more accessible, economically and technologically. Getting a dispenser with an alkaline water filter is far more affordable than one with a water ioniser, both in terms of upfront and running costs. Due to its sophisticated circuitry, a water ioniser costs a pretty sum to purchase and racks up utility bills any time its running. With its myriad settings, the water ioniser also has a learning curve that the busy or technologically disinclined consumer will not appreciate. In contrast, the alkaline water filter only incurs costs during replacements, and needs no training to use.
Alkaline water filters are also small and portable, allowing their implementation in portable jugs or bottles that you can bring on holidays or picnics for a constant supply of alkaline water. While the alkaline water filter appears to be the practical choice, the water ioniser should not be dismissed outright. Besides offering a variable pH level where the alkaline filter’s is fixed, the water ioniser does not need filter replacements. This means that as you scale up your water consumption – in a particularly big household, perhaps – the initially large investment in a water ioniser gradually pays for itself by doing away with the constant need for filter replacements. As technology advances, water ionisers will only become more affordable and may give alkaline water filters a run for their money someday.
Which Process Is Right For Me?
Thankfully, in some cases, the choice is already made for you. Portable alternatives for alkaline water most commonly employ an alkaline water filter thanks to its small size and independence of a power source. However, for home or office usage, you would most certainly have to do some personal cost-benefit analysis. Would the huge upfront cost of a water ioniser be offset by your savings in filter replacements? Can your household or office comfortably use a new digital interface for getting water? Do you need the additional functions of a water ioniser?