Tap water: can we trust it, or should we filter it?

Written by: Natalie Louise Burrows


Healf Journal

The conversations around tap water and filtering it have exploded in the past few weeks since the news headlines hit about the water quality in the South West. On Wednesday, 15th May, The UK Health Security Agency confirmed an initial 22 cases of cryptosporidiosis (a parasitic infection that causes diarrhoea) in the Brixham area of Devon. More than 100 people also reported symptoms to their GPs around the same time - and by the 23rd of May, this had risen to 100 people actively infected and suffering.

Meanwhile, in the Beckenham area of South East London, a suspected outbreak has potentially contributed to dozens of people falling ill with vomiting and diarrhoea lasting up to two weeks and, in some cases, causing such severe dehydration individuals are requiring hospital treatment.

Tap water comes from lakes, rivers, reservoirs, and groundwater. Prior to reaching our taps, it should be screened, cleaned, aerated (to remove gases and volatile compounds), and disinfected to eliminate pathogenic microorganisms that contribute or cause illness. Finally, underground water pipes transport it from the storage tanks to our taps and hey presto.

So, we currently have two key questions: 1. Are the water companies doing enough at the water tank sites to actively ensure their systems are ‘cleaning’ the water effectively before it is distributed? and 2. Are the pipes within the underground water transportation network contributing to contamination after the screening process has concluded?

We may not be able to answer these questions in this article (but we should certainly be asking this of our MPs and water companies). We can look at what filtering water means, the particles that are causing concern and what you need to know when it comes to filtration methods.

Natalie Louise Burrows, Registered Nutritional Therapist and Clinic Director of Integral Wellness, a nutrition and health clinic specialising in CardioMetabolic Health, dives in.

What does it mean to filter water?

Filtering water refers to the process of removing impurities, contaminants, and undesirable elements from water to make it safer and more palatable to drink. This can include the removal of physical debris, chemicals, and biological contaminants through various filtration methods - basically, what the water companies should be doing!

However, as we have seen recently (and have also been aware of for some time), the methods used by water companies do not filter all undesirable elements from the water that end up coming out of our taps. Therefore, home filtration systems are becoming more widely available, allowing you to filter your water again yourself and have confidence in the quality of what you’re consuming.

Remember, it’s not only the water we drink but also what we cook and bathe in. We absorb water through our skin, and food absorbs water when cooking. 

Should we filter tap water?

Despite water plants' screening and cleaning process, many contaminants escape the cleaning process before being distributed across the old Victorian water networks.

The cleaning process should remove bacteria, viruses, parasites, algae, insects, dissolved particles, dust and chemicals. However, many other chemicals are used as part of the filter process, and some substances escape the process altogether.


UK water companies use chlorine or chloramine, a compound of chlorine and ammonia, as a disinfectant to maintain the safety of drinking water throughout the distribution system.

The levels of chlorine should be controlled and monitored to meet safety standards. However, while chlorine effectively disinfects water, it can react with organic matter to form disinfection by-products, such as trihalomethanes, which have been linked to health concerns like bladder cancer . Chlorine can also cause irritation to the skin, eyes and airways.


Fluoride has been added to UK water supplies to help prevent tooth decay. Around 1mg of fluoride per litre of water is meant to be present and is considered by the government a beneficial and positive movement for dental health.

However, the World Health Organisation has regulated 1.5mg/L as the upper limit as excess amounts of fluoride are toxic to the body and can cause dental and skeletal fluorosis (white and brown speckles on the teeth and bones) as well as arthritis, bone damage, osteoporosis, muscular damage, fatigue, joint-related problems, and chronicle issues. It could adversely damage the heart, arteries, kidney, liver, endocrine glands, and neuron system in extreme conditions.


Polyfluoroalkyl substances (PFAS) are man-made chemicals used in industrial manufacturing for products such as non-stick cookware, furniture, and carpets. They are called "forever chemicals" because they are nearly indestructible in both the natural environment and our bodies. It is estimated that almost everyone in the world has PFAS in their blood.

Analysis has revealed that 37% of water courses tested in England and Wales contain medium or high-risk levels of PFOS and POAS - types of PFAS, aka forever chemicals. Recent tests in London showed levels of PFAS at 1.4 times the maximum limit.

There is evidence that PFAS carry health concerns, including cancer, thyroid disease, autoimmune conditions and fertility problems. However, currently, testing for forever chemicals is only required if they are found to be high levels and not as standard .

Use the interactive map here to check for PFAS levels in your area.


Antibiotics, antidepressants, oral contraceptive pills, pain killers, beta blockers and anti-psychotics are all commonly prescribed medications. Medication is not utilised 100% in the body, and a certain amount is expected to be excreted through urine, which naturally enters the water system. Some people also flush unused or old drugs down the toilet as a way of disposing of them ‘safely’. However, this is backfiring (please don’t do this)!

Water plants' cleaning and filtration systems cannot filter all chemicals, and small nanoparticles can get through. Recently, a high level of drugs was found in marine life off the South coast of England, calling into question (again) the quality of our waterways and the concerns for pharmaceuticals and recreational drugs, such as cocaine, in our water system.

Other chemicals

Our tap water comes from groundwater, and due to the ‘run-off’ from the agricultural system, mining waste, power plants, corrosion of water system, etc., other chemicals are also of concern, including:

  • Pesticides and herbicides - a pest repellant known to disrupt the endocrine system (aka hormones), they can also cause gastro symptoms and skin and immune conditions.

  • Nitrites/nitrates - chemical fertilisers with nitrite are significantly more toxic. However, both can cause oxygen deprivation in infants and potentially increase cancer risks.

  • Heavy metals—mercury, lead, aluminium, arsenic, and cadmium—are all known to be toxic to the body and can cause brain and nervous system damage if exposed to high levels. Heavy metals either need to detoxify from the body or will be stored in the bones and tissues, meaning ‘safe’ amounts can accumulate over time.

These contaminants may severely impact some people, but not all, because we are all individuals. One person's experience is often very different from another due to multiple contributing factors.

Nevertheless, given these contaminants and the current outbreak of bacterial infections due to polluted tap water in the UK, do you feel it is time to filter your water? 

Does filtering pull out all the beneficial minerals?

Some filtration methods remove harmful substances and strip the water of beneficial minerals like calcium, magnesium, and potassium. These essential minerals play crucial roles in maintaining good health and balancing the water's pH level. Without them, water can become more acidic, affecting its taste and potentially leading to health issues over time.

The absence of these minerals also impacts the body's electrolyte balance, which is essential for hydration, nerve impulses, muscle function, and maintaining stable blood pressure. Drinking demineralised water over long periods can lead to deficiencies in these crucial nutrients, potentially causing issues such as weakened bones, muscle cramps, and impaired metabolic functions. Mineralised water is better at hydrating the body as the presence of electrolytes aids in the absorption and retention of fluids.

When passing water through filtration systems, it’s essential to consider remineralising. This process can involve adding back naturally occurring minerals or using mineral cartridges in filtration systems. By doing so, we ensure that our drinking water supports our needs, is void of the substances we don’t need and full of the essential minerals we do need.

What is the best way to filter water?

The best ways to filter water depend on the specific contaminants you want to remove as well as your budget and household space/set-up, however, here are some options:

Reverse osmosis

Reverse osmosis is built into the central water system of a home. It is an effective water purification method using a semipermeable membrane to remove contaminants by forcing water through under pressure. It eliminates harmful substances, including bacteria and dissolved solids, producing clean water. However, reverse osmosis also removes beneficial minerals such as calcium, magnesium, and potassium, so choose a system that also remineralises the water.

Examples: UK Water Filters Reverse Osmosis System with Pump

Alkaline water filters

Alkaline water filters increase the pH level of the water by adding minerals. The filtration process typically involves multiple stages, including an initial purification phase to remove contaminants, followed by the addition of minerals like calcium, magnesium, and potassium. An alkaline filter system is a good option if space is an issue.

Examples: Aqua True Water Filter & Phox Water Filter

Activated carbon filters

Activated carbon filters are widely used in water purification to remove impurities and improve taste and odour. These filters use activated carbon, a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption. Activated carbon filters are particularly effective at removing organic compounds and chlorine and are a good option if countertop space is available.


This article is for informational purposes only, even if and regardless of whether it features the advice of physicians and medical practitioners. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The views expressed in this article are the views of the expert and do not necessarily represent the views of Healf