What's in UK Tap Water? PFAS, Chlorine & Filtration

What is actually in UK tap water? UK mains drinking water is carefully treated and regulated, but that does not mean it contains nothing beyond H₂O. Water can contain residual chlorine, disinfection by-products, traces of pesticides, naturally occurring minerals and, in some supplies, other chemicals that water companies monitor closely. Understanding these substances is the first step towards choosing the right water filtration system for your home.

At East Midlands Water Company, we believe you should know what is in your water and how to improve its taste and quality. In this guide, we explain the contaminants discussed in our latest video, what independent research says about them, and why the BT65 whole-house water filter is our recommended solution for whole-house activated carbon filtration.

1. Chlorine in UK tap water: why is it added?

Chlorine is intentionally added during drinking water treatment because it kills or inactivates microorganisms. A small residual helps protect water as it travels through the network of pipes supplying homes and businesses.

The Drinking Water Inspectorate explains that some people are particularly sensitive to the taste and smell of chlorine, even at low concentrations. If your tap water has a faint swimming-pool-like smell or taste, residual chlorine may be the reason.

Can a water filter remove chlorine? Yes. Activated carbon is an established method of removing chlorine and reducing the associated taste and smell. A whole-house carbon filter treats the incoming mains water supply, rather than only the water delivered through one drinking-water tap.

2. Trihalomethanes (THMs): what are disinfection by-products?

Trihalomethanes, or THMs, can form when chlorine used in drinking water treatment reacts with naturally occurring organic material. Chloroform is one example of a trihalomethane.

The UK drinking water standard for total THMs is 100 micrograms per litre (µg/L). This is set out in the Water Supply (Water Quality) Regulations 2016.

Why does research pay attention to THMs? The US National Cancer Institute describes studies associating greater exposure to some drinking-water disinfection by-products with an increased risk of bladder cancer. An association in research is not proof that drinking UK tap water at regulated concentrations causes cancer.

Can activated carbon reduce THMs? Granular activated carbon significantly reduces many adsorbable organic compounds, including certain disinfection by-products and their precursors. The extent of removal depends on the specific compound, water quality, flow rate and condition of the carbon media.

3. Pesticides and herbicides: can they get into drinking water?

Agricultural pesticides and herbicides help control insects, plant diseases and weeds. Some can enter rivers and groundwater through runoff or leaching, meaning water suppliers need to monitor for relevant substances and treat water where necessary.

The Drinking Water Inspectorate's pesticide guidance confirms that water companies have invested in activated carbon treatment, sometimes alongside ozone, to help safeguard drinking water supplies.

Does activated carbon remove pesticides? It can be effective for many pesticides and herbicides, although not every chemical is captured equally well. This is one reason a properly sized carbon bed and appropriate maintenance matter.

4. PFAS and 'forever chemicals': are they found in UK tap water?

PFAS stands for per- and polyfluoroalkyl substances, a large family of manufactured chemicals used in products including water-resistant clothing, non-stick cookware, some food packaging and firefighting foams. Many PFAS persist for a long time in the environment, which is why they are often called forever chemicals.

According to the UK Health Security Agency, some better-studied PFAS, including PFOA and PFOS, have been linked with changes in cholesterol, immune response and other possible health effects. Risks depend on the specific substance, concentration and duration of exposure.

Have PFAS been detected in UK drinking water?

Yes, PFAS are a focus of monitoring by the Drinking Water Inspectorate. Its report covering 2025 records two Tier 3 detections of PFOS in treated water.

This is not just a scientific discussion. On 5 November 2024, MP Munira Wilson raised concerns about PFAS in drinking water in the House of Commons, proposing stronger regulatory controls. You can read the official Hansard record and view the original parliamentary recording. This parliamentary discussion is referenced for public-interest context and does not imply endorsement of any product by Parliament or an MP.

Can activated carbon remove PFAS?

Yes. The US Environmental Protection Agency (EPA) identifies granular activated carbon (GAC) as an established technology for reducing certain PFAS. Longer-chain compounds such as PFOA and PFOS are generally captured more effectively than shorter-chain PFAS, which can break through carbon more quickly.

This distinction is important: evidence that GAC can reduce certain PFAS does not establish a fixed PFAS removal percentage or treatment capacity for every domestic carbon filter.

5. Volatile organic compounds (VOCs): what are they?

Volatile organic compounds, or VOCs, are a broad category that includes some industrial solvents and other organic chemicals. Examples include trichloroethene and tetrachloroethene, which are regulated in drinking water.

The EPA's overview of drinking water treatment technologies identifies granular activated carbon as an effective treatment for many VOCs.

6. What about lead, heavy metals and fluoride?

Lead and selected heavy metals: The BT65 product information includes lead and selected heavy metals among substances it can help reduce, but different dissolved metals require different treatment approaches. If you have old lead pipes, the priority is to identify and replace the source of lead. Water can pick up lead from plumbing after passing through a whole-house filter; the Drinking Water Inspectorate provides guidance on lead pipework.

Fluoride: Fluoride can occur naturally in water and is also added to some public supplies to help prevent tooth decay. UK drinking water has a maximum permitted fluoride concentration of 1.5 mg/L, and the DWI explains how fluoridation is managed.

Standard activated carbon should not be relied on to remove fluoride. For households that specifically want to reduce fluoride, we offer an optional fluoride-reduction media version of the BT65, using specialist media alongside the whole-house filtration system. You can choose that option on the standard BT65 product page or the high-capacity BT65 page. Fluoride reduction depends on media selection, incoming concentration and operating conditions.

7. Why is coconut-shell activated carbon so effective?

Activated carbon is produced to create an extensive network of tiny pores, providing an enormous internal surface area. Many dissolved organic compounds attach to the carbon by a process called adsorption. Chlorine removal also involves reactions at the carbon surface.

Coconut shells are one of the materials used to make granular activated carbon. The EPA explains how GAC works and why it is widely used for taste, odour and selected organic compounds.

The BT65 combines silver-impregnated coconut-shell granular activated carbon with twin sediment riser filters. Silver is included to help inhibit microbial growth on the filtration media. A 2026 study published in Chemosphere found that silver-loaded activated carbon suppressed bacterial proliferation and biofilm formation compared with the unsilvered carbon used in that study. That research examined the material in a continuous-flow test system; it was not a test of the BT65 and does not make the BT65 a water steriliser.

Unlike a water softener or reverse osmosis system, conventional carbon filtration does not normally remove the dissolved calcium and magnesium that occur naturally in water. That means you can reduce chlorine taste and odour while retaining these minerals. If your main issue is limescale, you need a water softener, not a carbon filter.

8. Why choose the BT65 for whole-house water filtration?

Most people think about filtration only at the kitchen sink. But chlorine taste and contaminants in the water are not limited to the glass of water you drink. A whole-house water filter is fitted to the incoming mains supply, so water is treated before it reaches the property's taps, showers, baths and connected appliances.

Our BT65 whole-house water filter is one central filter for your home, using premium silver-impregnated coconut-shell carbon and twin sediment risers. It provides a practical solution for reducing chlorine, sediment, unpleasant tastes and odours, and a range of adsorbable organic compounds.

Which BT65 model is right for your home?

Standard BT65 — up to 650,000 litres: Suitable for many homes with approximately two to three bathrooms, with a published replacement interval of up to three years depending on use and water quality.
High-capacity BT65 — up to 1,350,000 litres: Designed for larger properties and higher demand, with 1-inch connections.
Optional fluoride-reduction media: Available when selecting either BT65 product, for households that specifically want to target fluoride.

Frequently asked questions about UK tap water and filtration

Does a whole-house water filter remove chlorine?

An activated carbon system like the BT65 removes chlorine and improves taste and odour. The BT65 is installed on the incoming mains supply, so it treats water going to multiple outlets in the home.

Can the BT65 remove PFAS or forever chemicals?

Granular activated carbon is an established technology for reducing certain PFAS, particularly some longer-chain compounds. That research does not guarantee a specific PFAS reduction level for the BT65 as there are many types of these chemicals across different water supplies.

Does the BT65 remove fluoride from UK tap water?

The optional fluoride-reduction media model is the relevant BT65 choice for targeting fluoride.

Does activated carbon remove beneficial minerals and electrolytes?

No. Activated carbon leaves dissolved minerals such as calcium and magnesium in the water. It is not the same process as water softening or reverse osmosis.

Does a whole-house filter stop limescale?

No. Limescale is caused by water hardness. If your goal is to prevent limescale, pair your whole-house filtration with a suitable water softener.

Can a BT65 remove lead and heavy metals?

Yes. The BT65 removal list includes lead and selected heavy metals among its filtration. Removal depends on the specific metal. A filter does not replace the need to remove lead pipes or fittings, especially where lead can enter the water downstream.

How long does a BT65 filter last?

The standard model lasts up to 650,000 litres or up to three years, depending on household usage and water quality. These figures do not mean every contaminant will be removed to the same extent throughout that period.

How can I check what is in my local tap water?

Ask your water supplier for its latest water-quality report for your postcode. If there is a specific contaminant you are concerned about, use the report or a suitable laboratory test to help choose the right treatment.

Take control of your whole-house water quality

You do not have to believe UK tap water is generally unsafe to want better-tasting water or extra filtration. Whether your main priority is removing chlorine, improving taste and odour, or understanding the options for particular contaminants, the right approach starts with good information.

For homes wanting a centrally installed carbon filtration system, the BT65 is our recommended whole-house solution. Explore the standard BT65 water filter and high-capacity BT65, including the optional fluoride-reduction media. If you are unsure which system suits your pipework, property or water-quality concern, contact East Midlands Water Company for guidance before ordering.

Research and references

The article is based on publicly available regulatory information and research.

What's Really in UK Tap Water? Chlorine, PFAS, Pesticides & How to Filter Them