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What is the most significant factor in determining whether water is safe…

- - - - Water in Australia is heavily regulated, one of the most regulated worldwide due to the ADWG (or Australian Drinking Water Guidelines), this means that the water we drink is generally sanitary and safe to drink
      - HOWEVER our drinking water isn't just pure water, it is made up of a lot of different components with some being more harmful than others.
        
        Components of tap water
        
        Water, H20
        
        Chlorine
        
        Ranges between 0.2 - 5 mg/L
        
        This is added as part of the process of making drinking water, water from rivers, lakes, underground aquifiers, etc, safe to drink. Chlorine works to protect drinking water from micro organisms, bacteria, diseases, viruses and ameoba such as:
        
        Escheria Coli (causes stomach aches, severe food poisoning and diarrhea) [Cleveland Clinic, 2023]
        
        Salmonella (causes fever, stomach cramps and diarrhea) [Mayo Clinic, N/A]
        
        Listeria (although safe in small amounts, very dangerous to elderly and infa
        
        Degrades in UV
        
        Fluoride
        
        Occasionally added to try and stop tooth decay or work against tooth decay
        
        Fluoride is added to water at water treatment plants and has found positive outcomes, improving the number of cases of tooth decay. It's safe to drink, and generally only 1mg/L is added. [Victoria Department of Health, 2026[
        
        What's in our water?
        
        Chloramine NH2CL More stable, added into our drinking water
        
        Carbon Dioxide CO2
        
        Ammonia NH3 (fertilisers + industrial waste)
        
        Aluminum Al
        
        Trihalomethanes chemical compounds derived from methane
        
        Copper Cu
        
        Nitrates NO3 (come from fertilisers + pollution)
        
        Trace contaminants
        
        PFAs (synthetic chemicals)
        
        Heavy Metals (Lead, Copper) depending on the infrastructure
        
        Agricultural Pesticides
        
        PFAS "Australia has recently made headlines for its PFAS regulations being significantly more relaxed than guidelines elsewhere, with our standards allowing levels 140 times higher than those recommended in America. These so-called “forever chemicals” have been detected in drinking water supplies across Australia, with Sydney’s water utilities recently being called out for having PFAS contamination in town water reservoirs." - Complete Home Filtration
        
        Also known as Per- and poly-fluoroalkyl substances they get into water by not properly being disposed and as they do not break down they instead leach into our waterways. They affect humans by increasing cholesterol, altering our immune functions, thyroid disease and an increased risk for cancers
    - - It's a popular form of water, most people have had bottled water in the past, but is it safe?
        YES
        Drinking water is considered to be safe, it has however been found that majority of bottled waters are contaminated with microplastics, found in a study done by WHO (World Health Organization) [BROWNE, 2018]
    - - Boiled Water generally takes 1-3 minutes, for the boiling to have an effect
      - Boiled water does not remove chemicals HOWEVER it does work to inactivate bacteria, viruses and parasites that could later cause illness [Zip Water, 2025]
  - - - Surface Water which is where most of the populations drinking water comes from, found in rivers, streams, lakes and comes from rain/storms
        
        Ground water supplies 30% of our populations water, still comes from the rain but instead it's water that seeps into the ground and is then put through natural aquifers (permeable layers that hold water). This water is then found through a well, getting pumped out or via natural springs. [Culligan Australia, 2023]
      - What does the water go through
        
        Screening: removing any large solid objects that could be found in the water (logs, fish, branches, etc)
        
        Flocculation: this is done to remove any fine particles that aren't removed through screening. This is done by using chemicals which cause the particles to clump together and sink to the bottom of the water.
        
        Filtration: The water is moved through sand or a mixture of sand and crushed coal which filters out any of the clumped particles
        
        Disinfection: Chlorine is added in numerous ways -> Bubbling chlorine gas through the water -> Sodium hypochlorite which is a liquid chlorine is added in automated doses into the water -> Calcium hypochlorite, an unpopular solution which involves dissolving solid chlorine into water and then adding it to a larger body of water.
        
        Fluoride: Automated dosing is used to add fluoride to the water. These come in 3 main forms. Fluorosilicic acid ( a liquid used in larger plants), sodium fluoride (a powder) and sodium fluorosilicate (a crystal) -> both used for smaller amounts of water
        [Water NSW, 2026]
        
        How does the water get to us?
        
        Water once treated can then be stored in towers and tanks, the water gets here via underground pipes. Once the water is in because it's suspended up high the water wants to move downwards where there are normally pipes, this water pressure allows for the water to go through the pipes, flowing through main and service pipes until it gets to your house (or whatever needs drinking water)
        
        Here are the types of pipes
        
        Copper
        
        PVC Polyvinyl Chloride
        
        Polyethylene
- - - - Disinfecting chlorine involves hypochlorite (OCl) or hypochlorous acid (HOCl). When water is especially alkaline, it shifts the balance of HOCL in water, instead it begins to take more of the form of OCL. This is previously mentioned as a slower disinfectant, and overall just less effective, especially for large amounts of water which is the norm for water treatment. This makes water less safe. [Provitab 3, 2025]
  - - - Naturally occuring mineral, worsened by industrial and agricultural activity. It can cause bladder, lung and skin cancer. It leaches from rocks and soil getting into our grand water.
        
        There should never be more than 0.01 milligrams per Liter,
        
        To test for arsenic you can use a DIY at home kit. This means mixing the water with reagents. The first one is colorimetric tests. The water is treated with an acid, generally nitric acid or hydrochloric acid, it stops arsenic from binding to container walls to get a more accurate reading of the arsenic amount. This is caused because the acid stabilizes the arsenic, it stops the arsenic from binding to other elements which could be found in the water and also repels the arsenic from the side walls of the beaker or container. From here zinc powder is added This makes arsenide, a gas which is then collected in a closed off chamber where it meets a strip of mercuric bromide or HgBr2 which then creates a reaction which depending on the colour tells you how much arsenic there is. [David, 2021]
    - - Hexavalent chromium, or chromium-6 it enters drinking water from soil polluted by industrial usage. It's toxic and used in stainless steel welding, wood preservation, chrome plating to name a few. It causes cancers, severe tissue damage and immune hypersensitivity [National Institution of Environmental Health Sciences, 2026]
        
        There should never be more than 0.05mg/L [NHRMC, 2
        
        The most accurate way is through professional lab testing, as with most tests for metals. However, you can use colour testing [WOODWORD, 2023]. The colour testing is similar to Arsenic but with different chemicals involved. You would first mix the water with chromium with an acid and then add diphenylcarbazide which then react to show a colour which you can use to find out how much hexavalent chromium there is. [KAPOOR, n/a]
    - - Manganese is naturally occurring and is found in food, water and soil. Small amounts are good however excessive amounts become dangerous. It is used in iron, steel and in general as an alloy. Through industrial pollution more manganese than usual can be added into the water which then becomes dangerous. Too much can cause headaches, fatigue, irritability and a loss of appetite. [ATSDR, 2014]
        
        There should never be more than 0.5mg/L as it will pose neurological risk. More than 0.1mg/L are also unwanted but more because of the metallic taste it leaves in water and also the discoloration of water. [Australian Drinking Water Guidelines, 2011]
        
        Nitric acid is added to balance the pH. Alkaline Cyanide is added to the water. What happens is the alkaline cyanide binds with other metals in the water to stop them from interfering with the testing. Then PAN (1-(2-Pyridylazo)-2-Naphthol) is added to react with the manganese in the water. It causes an orange-red colour.
    - - Mercury is a neurotoxin which gets into water from industrial pollution, mining waste and coal based power plants. Methylmercury is an organic but rare form of mercury in water. It can create impaired hearing and vision, loss of motor control, trembling, numbness and a tingling sensation (especially around hands and feet).
        
        There should not be more than 0.001mg/L.
        
        To test for mercury you use a chemically activated sheet and a dye called rhodamine which indicates how much mercury there is.
    - - Lead comes from corrosion in pipes that get water to your house. For example, copper pipes used to be soldered together with a lead based substance. This lead although banned since the 1980s, in old homes or unreplaced pipes the lead can leach into drinking water. It has many symptoms including, but not limited to, memory issues, headaches, adominal pain, muscle pain, high blood pressure, developmental issues, irritability, weight loss, vomiting, constipation, hearing loss, seizures, fatigue, loss of appetite [Mayo Clinic, 2026]
        
        There are no safe amounts of lead but the limit is no more than 0.005mg/L MAXIMUM. But water should not have any lead at all.
        
        You can use a color changing strip to test for lead.
- - - - -> Tap Water
      - -> Distilled water
      - -> Spring Water
      - -> Water Vapour
      - -> etc