When you pour yourself a glass of tap water, you probably don't think much about the journey it has taken to reach your home. From reservoirs and rivers to treatment plants and underground pipes, drinking water travels a long way before it reaches your kitchen.
In many countries, tap water is highly regulated and considered safe to drink. But "safe" doesn't necessarily mean your water is clean.Â
Understanding what's in your water isn't about creating fear—it's about making informed choices. Whether you're curious about improving the taste of your water or considering a filtration system, knowing the basics is the first step.
Common Drinking Water Contaminants
The word contaminant simply refers to substances that may be present in water. Some are intentionally added during treatment, some occur naturally, and others can enter the water as it travels through pipes.
Here are some of the most common.
Chlorine
Chlorine is one of the most widely used disinfectants in public water systems. Its job is to kill harmful bacteria and viruses, making drinking water safe during transport from treatment plants to your tap.
While chlorine plays an important role in public health, it can also affect the taste and smell of water. If your tap water reminds you of a swimming pool, chlorine is often the reason.
Many people choose to filter chlorine simply because they prefer the taste of filtered water.
Lead
Lead is rarely found in treated water leaving a treatment plant. Instead, it can enter drinking water through older plumbing, lead service lines, or outdated fixtures.
Because lead has no taste, smell, or colour, the only way to know if it's present is through testing.
If you live in an older home, it's worth learning more about your plumbing and local water supply.
Sediment
Sediment refers to tiny particles such as sand, rust, or dirt that can occasionally find their way into drinking water.
These particles are often harmless but may make water appear cloudy or affect its taste.
Sediment can become more noticeable after maintenance work on local water pipes.
Hard Water Minerals
Many people have hard water without even realising it.
Hard water contains naturally occurring minerals like calcium and magnesium. These minerals are not considered harmful—in fact, they can contribute to your daily mineral intake—but they can leave limescale on kettles, coffee machines, and shower screens.
Hard water may also influence the taste of your drinking water.
Microplastics
Microplastics are tiny plastic particles that have been detected in oceans, rivers, bottled water, and tap water around the world.
Scientists are still studying their long-term effects on human health, but growing awareness has led many people to become more interested in understanding their water quality and the filtration options available.
PFAS (Forever Chemicals)
PFAS are a group of synthetic chemicals used in products such as non-stick cookware, waterproof clothing, food packaging, and firefighting foams.
They're often called forever chemicals because they break down extremely slowly in the environment.
In recent years, PFAS have become one of the biggest topics in water quality research as governments continue to update regulations and recommendations.
Pesticides and Nitrates
In agricultural regions, rainwater can carry fertilisers and pesticides into rivers and groundwater.
Modern water treatment removes many of these substances, and public water supplies are regularly monitored to ensure they meet strict safety standards.
However, concentrations can vary depending on local environmental conditions and water sources.
Heavy Metals
Heavy metals such as arsenic, mercury, or cadmium can occur naturally in some water sources or enter the environment through industrial activities. Public water suppliers regularly monitor for regulated metals, but levels vary depending on geography and local conditions.
Pharmaceuticals
Trace amounts of certain medicines have been detected in some water supplies. These usually enter waterways after passing through the human body or through improper disposal. Researchers continue to study their long-term environmental impact.
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Do You Need a Water Filter?
Whether you need a water filter depends on your local water quality, your household, and your personal preferences.
You might choose to filter your water because you:
- Prefer cleaner-tasting water
- Want to reduce contaminants
- Live in an older home with ageing plumbing
- Want to reduce your reliance on bottled water
- Simply enjoy having fresh, filtered water readily available
Choosing a water filter should be about finding a solution that works for your home—not simply buying the most expensive option.
The Bottom Line
Clean drinking water is something many of us take for granted, yet it's one of the most important resources in our daily lives.
While tap water is generally safe, its composition varies depending on where you live, how it's treated, and the infrastructure that delivers it to your home.
By understanding what's in your water, you can make confident, informed decisions about whether filtration is right for you.
At claii, we believe clean water should be approached with curiosity, not fear. Understanding what's in your water allows you to make thoughtful decisions that suit your home, your lifestyle, and your values. Whether you choose to drink tap water as it is or filter it, every glass should be something you enjoy with confidence.