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Signs My Tap Water Might Be Dangerous To Drink

Water – it’s literally one of three things we can’t survive without (the other two being food and oxygen). Given this fact, why are so many of us so nonchalant about what comes out of our taps? Contamination can happen at so many points before it reaches our cup, not the least of which can actually originate from inside our homes. More specifically, in poorly installed or maintained plumbing systems. So, what are some of the signs your tap water might be dangerous to drink?



Water that’s safe to drink should be clear, odourless and have no discernible taste. One super obvious way to check if your drinking water might be contaminated is to see if it’s turbid or cloudy. Cloudy water isn’t necessarily immediately dangerous to your health but it could be a sign of chemicals or pathogens that can absolutely make you very sick.

Having said that, don’t be alarmed straight away – sometimes you get a glass of water and it looks cloudy or milky and it’s completely harmless. Cloudiness can be caused by the water in the pipes being cooler or slightly more pressurised. The most likely (and more common) cause is tiny air bubbles in the water. This is known as “white water” and it’s created when water is delivered under varied pressures and mild temperature differences.

Luckily there’s a simple test to confirm if this is what’s happening or if it’s something more sinister. Just fill a clear glass and watch if the water clears from the bottom up. This is a clear sign (pardon the pun) that the cloudiness is simply air bubbles, and is completely fine to drink. However, of this isn’t the case, you should get in contact with Pro Plumber asap and have us test your water.



Water hardness is often characterised by a build-up of calcium or magnesium, which can leave elements in your sink, tap or drinking glass. It could also be the reason why your hands feel slimy after washing them with soap and water, or you have to use more laundry detergent to clean your clothes. Sydney’s water is generally considered to be soft, with a hardness level of about 50mg/L. Brisbane and Adelaide have some of the hardest water where it reaches nearly 100 mg/L.

Even so, hard water isn’t a sure-fire sign that your water source is contaminated. In some cases, it’s caused by an excess of calcium or magnesium, which shouldn’t pose immediate harm but it could be an indicator of increased presence of metals like aluminium, manganese, and lead. Again, if in doubt, get in contact with Pro Plumber and we’re happy to give you free assessment on your water condition.



Yellow water could signal the presence of chromium -6, the cancer-causing chemical that resulted in a lawsuit filed by clean water advocate, Erin Brockovich. Erin was a legal clerk and clean water advocate who was made famous by Julia Roberts’ Oscar-winning portrayal of her in the 2000 film that shares her name.

Don’t be alarmed by this though, in Australia, our drinking water is well-controlled and supplied by various natural water catchments around the country. However, while yellow tinged water may not be something we have to worry about, discoloured water does happen and in some cases, could be a sign of a buildup of various metals; iron, manganese, copper, or lead. If your water comes from a public system (ie not exclusively from a rainwater tank on your property) and is discoloured, a simple check is to see if it only appears while running cold water, which could be a sign that the water corporation is simply clearing out its pipes. This is considered non-harmful.



Blue or green water is often a sign of elevated levels of copper caused by corroded pipes. Though copper isn’t bad for you in small doses, high levels of exposure can produce health problems such as anaemia or liver and kidney damage.



Chlorine has been deliberately added to our water supply for the last 100 years. It successfully kills germs and pathogens. However, if mixed with other organic compounds, it can create a few harmful byproducts. One of these is a group of chemicals known as trihalomethanes (THMs), which have been linked to kidney problems and increased cancer risk. Another, known as haloacetic acids (HAAs), causes skin irritation and could also increase the risks of cancer.

On the flip-side, low levels of chlorine in the water system can also expose people to a parasite called giardia or cryptosporidium which causes diarrhoea, cramps and nausea. In 1998, Sydney went through a water crisis that apparently exposed a large number of our residents to this. Invariably, it was found to have been blown out of proportion and the levels of giardia in the drinking water was not as high as originally thought.

6. EXTREMELY RARE (and currently non-existent) in Sydney water but can happen…



Water that smells like rotten eggs could contain hydrogen sulfide. This is a naturally occurring, colourless gas that can be present in groundwater. When hydrogen sulfide is exposed to certain bacteria, it converts into sulfate, which can cause dehydration or diarrhoea. Sulfate levels above 250 mg/L may make the water taste bitter or like medicine, even without the smell. Thankfully this is not an issue in Sydney’s modern drinking water systems.


Barium is naturally-occurring chemical that can get into the water supply by drilling or manufacturing processes. If present, it can produce a fishy smell in the water. Fishy-smelling water could signal an excess of barium, a naturally-occurring chemical that can seep into a water supply through drilling or manufacturing. When barium is present above recommended levels, it could cause increased blood pressure, muscle weakness, or kidney, liver, and heart damage.

Water that smells fishy might also contain cadmium, a chemical found in lead and copper ores, which can leach into pipes through industrial waste. Exposure to elevated levels of cadmium in drinking water can cause kidney, liver, and bone damage. One simple way to check if your water is safe is to pour a glass from the tap and move to another room. After swirling the water around, if it still smells like fish, it could mean that contaminants are present.


All in all, we’re very lucky to have the high level of quality drinking water we have in Sydney. Compared to even other well-developed nations, we’re amongst the safest in the world. However, if you do notice any changes in your drinking water, it’s probably a good idea to get in contact with Pro Plumber. We can inspect your water and identify any issues you might have that could be coming from your plumbing system.