Bacteria in water - NZ
This is becoming more of an issue globally and in New Zealand we typically add chlorine to our water supply to remove the chance of bacteria entering the water supply.
Coliforms and E. coli are both types of bacteria commonly used as indicators of water quality, especially in assessing the safety of drinking water. Here's a brief overview:
Coliform Bacteria:
Definition: Coliform bacteria are a group of bacteria found in the intestines of warm-blooded animals. They serve as indicators of fecal contamination and potential pathogens in water.
Significance: The presence of coliform bacteria in water suggests the possible presence of harmful pathogens. Monitoring coliform levels is crucial for assessing water quality and ensuring the safety of drinking water supplies in New Zealand.
Escherichia coli (E. coli):
Definition: E. coli is a specific species of coliform bacteria commonly found in the intestines of warm-blooded animals, including humans. Certain pathogenic strains of E. coli can cause severe illness.
Significance: The presence of E. coli in water indicates recent fecal contamination and poses health risks, including gastrointestinal infections. Monitoring E. coli levels is essential for assessing water quality and ensuring the safety of drinking water supplies in New Zealand.
Ministry for the Environment & Ministry of Health. (2019)
Testing for coliforms and E. coli in water involves collecting samples and culturing them on specific media that encourage the growth of these bacteria. The presence and concentration of these bacteria in the water sample can then be determined by observing colony growth. Regulatory agencies often have guidelines and standards for acceptable levels of coliforms and E. coli in drinking water to ensure its safety for consumption.
Options to combat bacteria.
There are several methods commonly used to sterilize water to remove bacteria and make it safe for consumption:
Boiling: Boiling water is a simple and effective method to eliminate bacteria and other pathogens (Ministry of Health, 2020). Bringing water to a rolling boil for at least one minute is recommended to ensure microbial safety (Watercare, n.d.).
Chlorination: Chlorination is a widely used method in New Zealand for disinfecting water by adding chlorine-based compounds (Water New Zealand, 2017). Proper chlorination practices are essential for maintaining water quality and safety standards (Dunedin City Council, 2018).
UV Disinfection: UV (ultraviolet) light treatment is gaining popularity in New Zealand for water disinfection due to its effectiveness against bacteria and viruses (Environment Canterbury, 2021). UV systems are increasingly implemented in water treatment facilities across the country (Wellington Water, 2019).
Filtration: Filtration methods, such as activated carbon and membrane filtration, play a significant role in water treatment in New Zealand to remove bacteria and impurities (Watercare, 2020). Filtration processes are crucial for meeting water quality requirements and ensuring safe drinking water (Auckland Council, 2016).
Filtering Chlorine from water:
Filtration to remove chlorine from water typically involves using activated carbon filters. Activated carbon, also known as activated charcoal, is highly porous and has a large surface area, which enables it to adsorb (not absorb) chlorine and other impurities from water.
Here's how activated carbon filtration works to remove chlorine:
Adsorption: When water passes through an activated carbon filter, chlorine molecules and other impurities are attracted to the surface of the carbon particles and adhere to them through a process called adsorption. This effectively removes chlorine from the water, along with other volatile organic compounds and contaminants.
Chemical Reaction: In addition to adsorption, activated carbon can also chemically react with chlorine, converting it into harmless chloride ions. This reaction helps to further reduce the chlorine content of the water.
Activated carbon filters are commonly used in point-of-use and point-of-entry water filtration systems, such as faucet filters, countertop filters, under-sink filters, and whole-house filtration systems. They are effective at improving the taste and odor of water by removing chlorine and other unwanted chemicals.
It's important to note that activated carbon filters have a limited capacity and need to be replaced regularly to maintain their effectiveness. The frequency of filter replacement depends on factors such as the volume of water treated, the concentration of chlorine in the water, and the size and type of the filter.
References:
Auckland Council. (2016). Water filtration. Retrieved from https://www.aucklandcouncil.govt.nz/environment/water/water-quality/Pages/water-filtration.aspx
Dunedin City Council. (2018). Chlorination. Retrieved from https://www.dunedin.govt.nz/services/water/chlorination
Water New Zealand. (2017). Chlorination in drinking water treatment. Wellington, New Zealand: Water New Zealand.
Watercare. (n.d.). Boiling water. Retrieved from https://www.watercare.co.nz/Water-and-wastewater/Boil-water-notice
Watercare. (2020). Filtration. Retrieved from https://www.watercare.co.nz/Water-and-wastewater/Water-quality/Filtration
Wellington Water. (2019). UV treatment. Retrieved from https://www.wellingtonwater.co.nz/water-services/treating-water/uv-treatment/
Ministry for the Environment & Ministry of Health. (2019). Microbiological water quality guidelines for marine and freshwater recreational areas. Wellington, New Zealand: Ministry for the Environment & Ministry of Health.