We’ve become fluent in reading food labels. We compare ingredients, question additives, and think carefully about what we put on our skin. But when it comes to water, the thing we drink, cook with and shower in every single day,  most of us rarely pause.

We assume it’s just… water.

In countries with regulated systems, public water is carefully treated and monitored. That matters. But “regulated” doesn’t mean identical everywhere, and it doesn’t mean composition is irrelevant. If you’ve ever wondered whether you need a water filter, and which type actually makes sense, this guide is designed to help you choose one that suits you. 

What Can Be Present in Drinking Water?

Even in well-regulated water systems, traces of certain substances may be detected.  chemicals and biological agents can persist. The key word is trace. Presence does not automatically mean risk. Dose, duration and cumulative exposure all matter. Here are the categories most often discussed in research.

1. Microbial Contaminants

Water treatment systems are primarily designed to reduce pathogenic bacteria, viruses and protozoa. In most developed regions, this dramatically lowers infection risk.

Where infrastructure is inadequate or fails, enteric pathogens in drinking water remain a significant contributor to gastrointestinal illness globally (1). For households using private wells, microbial testing is particularly important. 

For most municipal systems operating within standards, microbial risk is considered low.

2. Disinfection By-Products (DBPs)

Chlorine protects public health by reducing microbial contamination. However, when disinfectants react with natural organic matter, they form by-products. Reviews have explored associations between long-term exposure to certain disinfection by-products and health outcomes, although regulatory limits are set to balance microbial safety with by-product formation (2). For many households, activated carbon filtration is used primarily to improve chlorine taste and reduce some by-products. 

3. Heavy Metals

Lead, arsenic, cadmium and mercury can enter water from natural sources or corroding infrastructure. Chronic exposure to certain heavy metals has been associated with cardiovascular and oxidative stress mechanisms in children (3). Risk depends heavily on geography and plumbing age. Where elevated levels are documented, targeted filtration can be beneficial. In low-risk regions, concentrations are typically within regulatory limits. 

4. Organic Micropollutants and PFAS

Pharmaceutical residues, pesticides and per- and polyfluoroalkyl substances (PFAS) are increasingly studied as “emerging contaminants.” Recent reviews highlight their environmental persistence and ongoing investigation into long-term impacts at low doses (4). In areas with documented PFAS concerns, reverse osmosis systems are often considered. In regions without identified contamination, risk may be minimal. 

5. Fluoride

Fluoride has been added to many public water systems for dental health, but its presence remains controversial in some communities. Understanding the science is key to evaluating its effects.

Fluoride: History and Context

Community water fluoridation began in the 1940s after evidence linked appropriate fluoride exposure with reduced dental caries. Critical reviews have explored potential physiological effects of ingested fluoride at higher exposures (5), and the 2006 U.S. National Research Council report emphasised the importance of total intake and dose consideration (6).

The European Food Safety Authority provides dietary reference values for fluoride intake (7), reflecting both benefits and safety thresholds. Some individuals choose to reduce fluoride exposure through filtration. Others are comfortable with regulated levels. This is often a values-based decision informed by total exposure rather than a binary “good or bad” narrative.

Emerging research is also exploring how fluoride exposure may interact with aspects of the human microbiome, though findings remain under investigation (10).

Water and Your Microbiome

Your body is an ecosystem. So is your home. Water doesn’t just hydrate, it interacts with the trillions of microbes on and within us.

Gut microbiome

While the gut microbiome is primarily shaped by diet, water quality may influence it indirectly. Drinking water with different mineral compositions can affect microbial diversity in the gut. Some studies suggest that water hardness and mineral content contribute to variances in community structure (8). 

Skin microbiome

Skin microbes are influenced by water pH and mineral content. Hard water (high in calcium/magnesium) has been linked with dermatological issues like eczema, possibly through effects on skin barrier function and microbial balance (9).

Oral microbiome

Fluoride and other ions in water impact dental plaque bacteria and enamel remineralisation. While fluoride can suppress cariogenic bacteria, excessive exposure may shift microbial balance (10).

Water Filter Types

No filter removes everything, and even the “best” choice depends on your water source, budget, and health priorities.  Here is a short guide to help you navigate which one to use:

1. Know What You’re Filtering

Before buying a filter, get your water quality data: 

• Read your local water quality report.
• Identify whether any contaminants approach regulatory thresholds.
• Consider your plumbing age.
• Clarify what actually matters to you: taste, hardness, specific compounds, or peace of mind.

2. Common Filtration Options

Here’s what typical types of water filters do:

3. Be Realistic About Marketing Claims

• “Detoxifies” and “alkalises” are frequently used in filtration marketing, but strong physiological evidence supporting these claims is limited.
• Removing all minerals isn’t always necessary, our diet supplies most essential minerals. 

So, Do You Need a Water Filter?

For some households, yes.

For others, perhaps not.

The decision becomes clearer when you:

• Understand your local water data
• Identify specific concerns
• Match the filter to your defined need
• Avoid reacting to broad, fear-driven messaging 

Science says: The benefits of filtration are highest when there are known contaminants above health-based thresholds (e.g., lead, arsenic). Routine filtration of already compliant municipal water may improve taste but offers limited health benefits (12).

The goal isn’t purity at all costs. It’s alignment.

Water is one of your daily inputs, just like food, light and the products you use in your home. Approaching it with curiosity, proportion and evidence allows you to make a decision that feels informed rather than urgent.

And that’s usually where the best health decisions begin.

Phoenix Water Filter

If you’re considering a filter, the Phoenix Gravity System is one worth exploring.

It uses activated coconut carbon and mechanical filtration to remove up to 99.9% of contaminants, including microplastics, heavy metals and PFAS, while retaining essential minerals. Housed in BPA-free stainless steel and powered simply by gravity, it sits neatly on your worktop with no plumbing or electricity required. The cartridges last up to 12 months, making it a practical long-term investment. 

Gutology readers can use code GT10 for £10 off* at phoenixwaterfilters.co.uk.

*single use, excludes sale periods.