What Contaminants Do Water Filters
Actually Remove?
Plain English explanations of what's in your tap water, where it comes from, and which filters actually remove it. No jargon, just the facts.
First, the Good News
UK tap water is among the safest in the world. Water companies test it constantly and must meet strict legal standards. This guide isn't about fear - it's about understanding what's in your water and making informed choices about filtration.
What's Actually In Your Water? (Plain English)
Here's what each contaminant is, where it comes from, and whether you should worry about it. Click any card for more details.
Chlorine
"The Swimming Pool Chemical"
What Is It?
Chlorine is the same disinfectant used in swimming pools. In much smaller amounts, it's added to tap water to kill harmful bacteria during its journey through miles of pipes to your home.
Where Does It Come From?
Water companies add chlorine at treatment works. It's intentional and regulated - your water company is required to maintain a safe level.
Real-World Example
That "swimming pool smell" when you run a bath or fill a glass. Some people can taste it in tea or coffee. Goldfish are very sensitive to it!
Calcium & Magnesium
"The Stuff That Furs Up Your Kettle"
What Is It?
These are natural minerals dissolved in water. They're what makes water "hard" and causes the white crusty buildup (limescale) on taps, kettles, and shower screens.
Where Does It Come From?
Hampshire sits on chalk and limestone rock. Rainwater dissolves these minerals as it filters through the ground into aquifers over thousands of years.
Real-World Example
The white flakes in your kettle, the crusty buildup around taps, the "tide marks" on shower glass, and why soap doesn't lather well.
Lead
"From Old Victorian Pipes"
What Is It?
Lead is a toxic heavy metal. It's NOT in the water supply - your water company's water is lead-free. The problem comes from old lead pipes inside some properties.
Where Does It Come From?
Before 1970, lead was commonly used for household water pipes. If your home has original Victorian or Edwardian plumbing, you may have lead pipes connecting to the mains.
Real-World Example
That dull grey pipe under your sink that looks soft enough to scratch with a coin - that might be lead. Modern pipes are copper (brown/gold) or plastic.
Nitrates
"Fertilizer Runoff"
What Is It?
Nitrates are nitrogen compounds used in agricultural fertilizers. They can seep through soil into groundwater supplies, especially in farming areas.
Where Does It Come From?
Farmers spread fertilizer on fields. When it rains, some washes into streams or soaks into the ground, eventually reaching water sources.
Real-World Example
You can't see, smell, or taste nitrates. They're completely invisible in water. This is why testing is important if you're in a rural area.
Microplastics
"Tiny Plastic Particles"
What Is It?
Microscopic pieces of plastic, smaller than 5mm. They come from the breakdown of larger plastic items, synthetic clothing fibres, and even car tyres.
Where Does It Come From?
When you wash synthetic clothes (polyester, nylon), tiny fibres wash down the drain. Plastic bottles degrade. Car tyres shed particles on roads that wash into water.
Real-World Example
Every time you wash a fleece jacket, it releases thousands of microscopic plastic fibres. These are now found in tap water worldwide - including the UK.
Bacteria & Pathogens
"Germs"
What Is It?
Microscopic organisms including bacteria, viruses, and parasites like Cryptosporidium and Giardia that can cause illness.
Where Does It Come From?
In mains water: extremely rare due to chlorine treatment. In private supplies (wells, boreholes, springs): can occur from animal waste, septic tanks, or surface water contamination.
Real-World Example
E. coli from animal waste, Cryptosporidium outbreaks (like the 2015 Lancashire incident). Private wells are particularly vulnerable after heavy rain.
Pesticides & Herbicides
"Weedkiller and Bug Spray Residue"
What Is It?
Chemical compounds used to kill weeds (herbicides) and insects (pesticides) in agriculture and gardens.
Where Does It Come From?
Agricultural spraying that washes into groundwater. Also from garden use - that weedkiller you spray on your patio can end up in water sources.
Real-World Example
Glyphosate (Roundup), atrazine, and other common weedkillers have been detected in UK water supplies, though always within legal limits.
Pharmaceuticals
"Traces of Medications"
What Is It?
Tiny amounts of prescription and over-the-counter medications that end up in water supplies.
Where Does It Come From?
When people take medication, their bodies don't absorb 100%. The rest is excreted and enters sewage. Treatment plants don't fully remove all drug residues.
Real-World Example
Hormones from contraceptive pills, antidepressants, painkillers, and antibiotics have all been detected in UK river water and sometimes tap water.
Heavy Metals
"Industrial Pollutants"
What Is It?
Metals like mercury, arsenic, cadmium, and copper that can be toxic at high levels.
Where Does It Come From?
Industrial pollution (historical), old plumbing (copper pipes can leach into acidic water), natural geological deposits.
Real-World Example
Green staining on sinks from copper pipes, or the infamous arsenic contamination in some wells. Less common in UK mains water.
VOCs (Volatile Organic Compounds)
"Chemical Vapours"
What Is It?
Organic chemicals that evaporate easily. Includes industrial solvents, fuel components, and cleaning chemicals.
Where Does It Come From?
Industrial contamination, petrol stations, dry cleaners, and underground fuel storage tanks that leak.
Real-World Example
The smell of petrol, paint thinner, or dry-cleaned clothes. If your water smells like chemicals (not chlorine), VOCs could be present.
Filter Types: What Each One Actually Removes
Not all filters are created equal. Here's an honest look at what each type can and cannot do.
Activated Carbon
The most common filter type. Uses carbon (often from coconut shells) that attracts and traps contaminants.
Excellent At Removing:
- ✓ Chlorine
- ✓ VOCs
- ✓ Pesticides
- ✓ Bad taste/odour
Does NOT Remove:
- ✗ Hardness
- ✗ Nitrates
- ✗ Bacteria
- ✗ Fluoride
Reverse Osmosis (RO)
Forces water through a membrane with microscopic holes. Removes almost everything - including beneficial minerals.
Excellent At Removing:
- ✓ Almost everything
- ✓ Nitrates
- ✓ Heavy metals
- ✓ Bacteria
Does NOT Remove:
- ✗ Some dissolved gases
- ✗ Some VOCs (pre-filter needed)
UV Sterilization
Uses ultraviolet light to kill bacteria and viruses. Doesn't remove anything - just makes it safe.
Excellent At Removing:
- ✓ Bacteria
- ✓ Viruses
- ✓ Parasites
Does NOT Remove:
- ✗ Chemicals
- ✗ Heavy metals
- ✗ Hardness
- ✗ Everything else
Sediment Filters
Physical barrier that catches particles. Like a very fine sieve for water.
Excellent At Removing:
- ✓ Sand
- ✓ Rust
- ✓ Dirt
- ✓ Large particles
Does NOT Remove:
- ✗ Dissolved contaminants
- ✗ Bacteria
- ✗ Chemicals
Ceramic Filters
Natural clay material with microscopic pores. Long-lasting and effective against bacteria.
Excellent At Removing:
- ✓ Bacteria
- ✓ Sediment
- ✓ Some heavy metals
Does NOT Remove:
- ✗ Viruses
- ✗ Dissolved chemicals
- ✗ Hardness
Quick Reference: Which Filter Removes What?
| Contaminant | Carbon | RO | UV | Sediment | Ceramic |
|---|---|---|---|---|---|
| Chlorine | ✓✓ | ✓✓ | ✗ | ✗ | △ |
| Lead | ✓ | ✓✓ | ✗ | ✗ | ✓ |
| Nitrates | ✗ | ✓✓ | ✗ | ✗ | ✗ |
| Bacteria | ✗ | ✓✓ | ✓✓ | ✗ | ✓✓ |
| Microplastics | ✓ | ✓✓ | ✗ | ✓ | ✓✓ |
| Pesticides | ✓✓ | ✓✓ | ✗ | ✗ | △ |
| Hardness | ✗ | ✓✓ | ✗ | ✗ | ✗ |
| VOCs | ✓✓ | ✓ | ✗ | ✗ | ✗ |
| Heavy Metals | ✓ | ✓✓ | ✗ | ✗ | ✓ |
| Pharmaceuticals | ✓ | ✓✓ | ✗ | ✗ | ✗ |
Hampshire-Specific Concerns
What's Actually in Hampshire Water?
- •Very high calcium/magnesium - The "hardness" that furs kettles. Not harmful, just annoying.
- •Normal chlorine levels - Standard disinfection. Easily filtered with carbon.
- •Low nitrates in urban areas - Higher in rural/agricultural zones.
- •No lead from mains - Only a concern if your home has old lead pipes.
When to Actually Worry
- ⚠Pre-1970 property - Get a lead test. Pipes may need replacing.
- ⚠Private water supply - Boreholes/wells need annual testing. No water company protection.
- ⚠Near agricultural land - Higher nitrate/pesticide risk. Consider RO if pregnant or with infants.
- ✓Normal mains supply - Generally safe. Filter for taste preference, not necessity.
Myth Busting: What Filters DON'T Remove
Jug Filters (Brita etc.)
Great for chlorine taste. But they DON'T remove:
- ✗ Bacteria
- ✗ Nitrates
- ✗ Hardness (barely touches it)
- ✗ Lead (some do, check NSF-53 certification)
UV Sterilizers
Excellent for killing germs. But they DON'T remove:
- ✗ ANY chemicals
- ✗ Chlorine
- ✗ Heavy metals
- ✗ Anything except living organisms
Magnetic "Softeners"
Despite marketing claims, magnetic devices DON'T remove:
- ✗ Anything at all
- ✗ Calcium or magnesium
- ✗ Any contaminants
- * No scientific evidence they work
Which Filter Do You Actually Need?
Just Hate the Taste?
Chlorine taste/smell bothers you
Health Conscious?
Want maximum contaminant removal
Old Property?
Concerned about lead pipes
Private Supply?
Borehole, well, or spring
Not Sure What Your Water Contains?
Rosebourne Plumbing offers water quality consultations for Hampshire homes. We can help you understand your water report, recommend the right filtration system, and install it properly.
