Understanding contaminants in tap water

When you turn on the tap, do you ever stop to wonder what is in your tap water, or where your water has come from?

Tap water contaminants in public water supplies are becoming an increasingly talked about topic. It doesn’t help that there are a lot of scare stories out there on the internet. This coupled with the use of the word ‘contaminant’ strikes fear in people across the UK.

But let’s be very clear. Tap water in the UK is highly regulated with standards being set by the Drinking Water Inspectorate (DWI) with clear guidance from the World Health Organisation (WHO).

While we believe it’s beneficial to empower yourself with knowledge, we don’t expect you to read the legislation as it can be heavy going but tap water contamination shouldn’t be something that scares you. Maximum permissible limits are set for microbiological, chemical, and metals contamination, with the point of compliance being at either the water treatment works or consumers taps.

The drinking water standards state that drinking water must be ‘wholesome’ and should not contain anything that might endanger human health. In simple terms, wholesome means anything that affects the look, smell or taste of the water making is unacceptable to drink.

We’ll highlight the most common contaminants in tap water shortly and reinforce our message as water filtration experts, that if you don’t want tap water contaminants in your drinking water you can filter them out.

Most common types of drinking water contaminants

It is vital to human health that we can access clean, safe drinking water in the UK.

16 billion litres of water per day is treated and supplied to taps across the UK.  

The quality of public water supplies in the UK is generally very high.

If you consider that in 2024, a population of 58.82M were supplied with water via 321,866 kms of pipe. It’s no mean feat to keep tap water contaminants to a minimum.

As the UK sources drinking water from rivers, aquifers, and reservoirs it must be treated to remove contaminants so that is looks, tastes and smells as best it can. Water treatment on this scale is a complex and challenging task involving multiple stages of filtration to remove chemicals, bacteria, viruses and pathogens.

Contaminated tap water MAY contain any of the following common tap water contaminants.

A word of warning here, just because there’s a list here doesn’t mean you have contaminated tap water.

The overall quality of UK tap water is excellent. And remember, you can access a water quality report for drinking water in your area by visiting your water suppliers website. Or, you can have your water independently tested.

 

Category	Contaminant	UK legal limit
Metals	Lead: A risk in pre-1970 properties that have lead pipes or lead soldering.	10 µg/L
	Copper: Can leach from copper pipes.	2 mg/L
Microbiological	E. coli, Coliforms, Cryptosporidium Very rare occurrences in UK tap water. Any failures trigger immediate investigation and remedial action.	0 per 100ml
Taste & Odour	Chlorine: UK mains water is treated with small amounts of chlorine to keep it disinfected and stop harmful organisms growing in it. Can affect taste / odour of drinking water.	No statutory limit but typical range is between 0.2-0.5 mg/L
	Chloramine: In some UK supplies a small amount of ammonia is added to water to disinfect it.	No statutory limit but resulting nitrite maximim is 0.5 mg/L
	Iron: Can cause discolouration if water passes through corroded cast iron pipes.	200 µg/L
	Manganese: sometimes occurs in distribution networks.	50 µg/L
Naturally occurring	Calcium & Magnesium: the hard water minerals	Can be aesthetically annoying but no health limits.
	Fluoride: Naturally occurring in all water sources. Only 10% of the population in England has fluoride added to household water.	1.5 mg/L
Disinfection by-products	Trihalomethanes (THMs): formed when chlorine (or other disinfectants) react with organic matter in the source water.	100 µg/L (total of 4 THMs)
Industrial / Emerging contaminants	PFAS: trace levels are being found in many UK tap water supplies.	100 ng/L (0.1 µg/L, UK guideline for sum of PFAS20)
	Microplastics: defined as plastics smaller than 5 mm. From plastic pollution and improper waste management.	No specific legal limit

 

µg – micrograms or one part per billion = one drop in an Olympic sized swimming pool.

mg – milligrams or one part per million = one drop in 100 litres

Further reading from Fountain Filters, the water filtration experts:

• Lead
• Fluoride
• PFAS / Forever Chemicals
• Hard water
• Microplastics

Sources of water contamination: human and natural causes

Would you believe that people are mostly responsible for contaminated tap water.

Human contamination in the form of industrial pollution, agricultural processes and domestic households all contribute to the presence of substances in tap water across the UK.

Not all these substances will present themselves as tap water contaminants. Water treatment plants across the UK work tirelessly to ensure that drinking water is potable. However, that’s not to say that sometimes trace amounts could be present.

Let’s look at the main human sources of water contamination in the UK.

Wastewater and sewage

Sewage and wastewater may contaminate water. For example, if a wastewater treatment plant malfunctions or sewers overflow after a bout of heavy rain, untreated sewage can enter rivers and seas.

And think about what we’re putting down our plugholes at home; detergent, oil, pharmaceuticals, microplastics. Our domestic wastewater may contribute to tap water contamination.

Industrial pollution

Industrial discharges, spills and leaks have the potential to introduce chemicals in tap water. This includes any discharges from legacy industries including closed mines. Although it’s heavily regulated in the UK, there is always the possibility that substances such as solvents, heavy metals, oil or other toxic substances could contaminate tap water.

Agricultural processes

The use of fertilisers and pesticides in agricultural processes can run off into groundwater and rivers. Bacterial contamination such as E. coli from slurry and animal faeces could be present in water supplies. E. coli in tap water is rare, and as the UK legal limit is 0 per 100ml any occurrence is investigated immediately.

Natural causes of water contamination in the UK

Nature also plays a part in tap water contamination.

Extreme weather events, natural minerals, animal waste, organic matter and erosion can impact the quality of water across the UK.

Contamination from natural sources in the UK falls into seven categories.

• Nutrients – erosion releases nutrients from soils and rocks into water.
• Microbial pollution – from wildlife waste such as birds, deer and fish.
• Sediments – soil enters rivers after rain, flooding, drought, and landslides.
• Chemicals/Metals – rocks and soil leach metals into the water.
• Organic matter – plants, peat, and leaves all decay and enter water sources.
• Salinity – saltwater intrusion into the groundwater in coastal areas.
• Algal blooms – warm sunny weather encourages natural algae growth in water.

The impact of emerging contaminants on water quality

Emerging contaminants are substances found in water that haven’t been monitored in the past but are being recognised and monitored now.

PFAS (forever chemicals) and microplastics, two high-profile contaminants have been found in rivers and groundwater in the UK, and subsequently as tap water contaminants. They both pose a potential risk to human health and the ecosystem, as well as the cost of treating UK tap water and the resulting pressure on the relevant authorities to legislate on permissible levels.

PFAS (Forever Chemicals)

PFAS or forever chemicals are they are often referred to are having a negative impact on the public water supply in the UK.

PFAS stands for Per- and polyfluoroalkyl substances and they come from non-stick coatings on cookware, stain resistant fabrics, food packaging, plastic bottles, firefighting foams and industrial coating.

They DO NOT break down naturally and are therefore present as chemicals in tap water.

Despite what you may read on the internet, you can remove PFAS in water relatively easily and cheaply.

Microplastics

When items we use every day such as synthetic clothing or plastic litter breakdown they create microplastics.

Microplastics are pieces of plastic 5mm or smaller, or 5 micron or smaller. It’s unlikely that you’ll be able to see microplastics in your tap water without the aid of a microscope, but they will probably be in there.

UK tap water supplies are seeing a relatively small problem with microplastics because of our failure to dispose of plastic waste properly.

On a global scale we’re still in the infancy of determining how much of a problem we have with microplastics in tap water and bottled water, but we know it’s there just based on the limited studies that have been done.

As experts in water filtration, we know that microplastics can be removed from your tap water.

If you’re keen to do more reading, this is an interesting paper. It’s the “first comprehensive study of the occurrence, concentrations, size distribution, shape, and polymer type of microplastics in 177 tap water samples from 13 cities in the UK, as well as 85 samples of bottled water from 17 popular brands, with various packaging materials, on the UK market.”

Tap Water Safety: Why It Matters ????

The UK has some of the safest tap water in the world, but regular checks are essential. Here’s why:

✅ Protects Health – Prevents bugs like E. coli and harmful chemicals from making people ill.
✅ Spots New Threats – Detects things like PFAS “forever chemicals” and microplastics.
✅ Checks Old Pipes – Finds problems where ageing pipes may release metals.
✅ Guards Against Pollution – Keeps sewage spills and agricultural runoff out of our drinking water.
✅ Manages Climate Risks – Helps deal with floods, droughts, and heatwaves.
✅ Builds Trust – Annual water quality reports keep everything transparent.

Safe water doesn’t happen by accident — it takes constant monitoring.

Our top 5 tips for fresher tap water

Reducing your exposure to tap water contaminants doesn’t have to be complex or expensive.

You might find some of the following tips useful.

1. Check your water - Ignore the scaremongering posts on the internet, take responsibility and look up the water quality report for your area which you’ll find on your supplier’s website.
2. Fix chlorine taste - Removing chlorine from tap water is a useful first step to reducing tap water contaminants. It will certainly improve the taste and smell of your water.
3. Watch for old pipes - If your home was built before the 1970s, use a lead-removal filter or ask about replacing pipes.
4. Tackle hard water - Consider installing a water softener or salt free conditioner to reduce limescale if you’re in a hard water area. It will save your sanity and protect your household appliances.
5. Choose the right filter by chatting to a water filtration expert - Yes, it’s amazing how many people end up buying a water filter that isn’t fit for purpose or is simply too complex for the job at hand. Talking to a water filtration expert like us will save you time and unnecessary expense.

How Fountain Filters can help you

When it comes to tap water contaminants Fountain Filters has you covered.

We provide clear, concise and honest advice whether you call us 01352 838 281, send a message via our helpdesk, or visit our website.

Contact us today.

FAQs

What are the most common contaminants found in tap water?

The most common tap water contaminants found in UK tap water today are chlorine, PFAS, microplastics, and lead.

What's in tap water in the UK?

UK tap water varies across the UK and contains primarily chlorine to keep it safe, calcium and magnesium (hardness minerals). Water may also contain heavy metals, nitrates, pesticides, microplastics and PFAS (forever chemicals).

Does boiling water remove chlorine?

Yes, boiling water does remove chlorine but it’s not as simple as filtering chlorine from your tap water. It takes approximately 4 minutes to remove 1mg of chlorine from 45 litres of water, so you’d need to know how much chlorine was in your water to determine how long to boil it.