Should you filter tap water?

Where does tap water come from?

Tap water comes from rivers, lakes, reservoirs and groundwater (water found underground in the cracks between rocks, soil and sand). The water is then screened, cleaned, aerated (to remove dissolved gases and volatile compounds) and disinfected to eliminate pathogenic microbes. Once processed, the water is transported from storage tanks to your taps via a network of underground water pipes. During this process, the water can come into contact with contaminants such as lead and bacteria in the pipes before it reaches your taps.

Contaminants in tap water

Despite tap water being cleaned, it still contains a number of harmful contaminants such as heavy metals and pesticides. The cleaning process only removes bacteria, parasites, dissolved particles, algae, insects, dust and some chemicals.

Water that is sourced from locations near to agricultural areas and manufacturing plants tend to contain more pollutants as they discharge large amounts of fertilisers/ soil chemicals, drug residues and organic matter into the water system.

Contaminants found in tap water include:

• Chlorine is used in as a disinfectant in tap water to kill bacteria, parasites and other microorganisms. The chlorine damages the cell wall of microbes so they cannot replicate and survive. Some drinking water smells highly chlorinated and this is because certain treatment plants use more chlorine than other plants. The adverse effects of chlorine include irritation (to airways, eyes, skin), breathing issues, wheezing, sore throat, dry skin and coughs.[1] [2]
• Chloramines are a group of chemicals that are formed when ammonia is added to water that contains chlorine. Treatment plants add ammonia to further disinfect the water as it extends the disinfecting life of chlorine. When chloramine interacts with organic matter it can produce disinfection by-products (DBPs) that are carcinogenic (cancer-causing) substances.[3] [4]
• Heavy metals: aluminium, lead, arsenic, cadmium, mercury are common toxic contaminants found in tap water. They enter the water system via industrial pollution, agriculture run-off, mining wastes and power plants. The main source of lead in drinking water is household plumbing systems – pipes, taps and plumbing fixtures are often made from lead. Corrosion of pipes and fixtures can leak lead into the water. These heavy metals are known to cause cancer, brain and nervous system damage, Alzheimer’s disease/ dementia, kidney failure, lung issues and toxicity to most organs in the body.[5] [6]
• Fluoride is added to drinking water to supposedly reduce tooth decay. Fluoride is a naturally occurring mineral found in all water as it’s released by rocks and flows into the soil, air and water. In some areas of the country, the fluoride levels in water are low so water plants add extra fluoride to the water to increase the amount of fluoride present in tap water. Too much fluoride can lead to tooth discolouration and tooth decay (especially in children) as the enamel can become weakened, neurological issues, seizures, joint weakness, low thyroid function, hormonal imbalance and acne.[7]
• Nitrates/ nitrites are chemical fertilisers used by the agricultural industry that ends up in septic tanks and wastewater treatment plants. Nitrites are much more toxic than nitrates; however, they are both known to increase cancer risk, affect foetal/child growth and development, and cause low oxygen levels in the blood of infants which can lead to neurological conditions like epilepsy and cerebral palsy.[8] [9]
• VOCs (volatile organic compounds) are chemicals emitted from gases that are released into the atmosphere and end up in the water system. VOCs are found in thousands of household products including air fresheners, deodorants, cosmetics, furniture, cleaning products, shoe polish, paint thinners and printing products. MTBE (Methyl Tertiary Butyl Ether) is a type of VOC that is used as a fuel additive for unleaded petrol. When water is heated and vaporised (such as in a hot shower), your body readily absorbs VOCs. They can damage the central nervous system, liver and kidneys, cause headaches and irritate the eyes, nose and throat. VOCs have also shown to cause cancer in both animals and humans.[10]
• PFAS (polyfluoroalkyl substances), also known as “forever chemicals” as they do not break down and stay in the body and environment for decades. PFAS are a group of man-made chemicals used in industrial manufacturing and a wide range of consumer products (stain-resistance carpets/ fabrics, cosmetics, non-stick cookware, water-repellent clothing) as they are resistant to heat, oil and water. They enter the environment by seeping into the soil and migrating to groundwater or rain water run-off where they end up in rivers, lakes and ponds. PFAS are linked to chronic health issues including asthma, cancer, infertility, liver damage and thyroid disease.[11]
• Pesticides and herbicides make their way to wastewater treatment plants via household drains, sewers, irrigation and rainfall that washes chemicals off agricultural areas and into lakes, rivers and streams. These toxic chemicals are linked to a whole host of negative health effects including hormone disruption, suppression of the immune system, skin conditions, gastrointestinal problems, neurological issues and cancer.[12] [13] Despite using various filtration techniques (such as oxidation with chlorine), wastewater plants are only able to remove around 60% of these highly toxic and persistent chemicals. 
• Pharmaceutical drugs and medications including antibiotics, mood stabilisers, pain killers, beta blockers and anti-psychotics (to name a few) can end up in water systems if they are not disposed of properly. This can happen if they are if they are flushed down the toilet or excreted in urine/ faeces, or via manufacturing facilities that are poorly controlled. Chlorination of waste water can remove some pharmaceutical drugs but not all. Even tiny amounts of these drugs may have an effect of some people’s health.[14]
• Cysts are microbial parasites that are invisible to the naked eye. They enter the water supply through lakes, rivers, sewage and leaking septic tanks. Cysts are resistant to disinfectant and chlorine so they cannot be killed off and can end up in tap water. Once ingested they often develop into parasites like Giardia and Cryptosporidium causing a host of problems in the body, especially the gastrointestinal and immune systems.

What about bottled water?

Bottled water comes from different sources – regular tap water (also called table water), spring water, mineral water or distilled water. Natural and spring water must be obtained from underground, unpolluted water sources and bottled directly at the water source. These types of bottled water have to adhere to strict guidelines and be safe to drink without the need for treatment or filtration (although some spring water has certain minerals/ substances removed). Natural water must also provide a specific mineral composition which has to be disclosed on the label. Table water is obtained from the same sources as tap water and must comply with drinking water regulations in the region where it is sold.

Not only is bottled water a more expensive option, there is the additional concern regarding the safety of plastic packaging. Most bottled water comes in soft plastic bottles made from polyethylene terephthalate (PET) which poses a health risk to both humans and wildlife. PET may leach hormone-disrupting chemicals (e.g., phthalates) into the water especially if the bottles are stored for prolonged periods of time or in elevated temperatures.[1] Drinking bottled water that has been left in a hot car is one of the worst things you can do!

Recent studies show that plastic bottled water contains excessive levels of microplastics (tiny fragments of plastic) including polypropylene, nylon, and polyethylene terephthalate – 50% more microplastics than in tap water.[2] Microplastics are the breakdown of plastic waste (bottles, bags, packaging etc) that winds up in oceans (harming fish and wildlife) and landfills. They are linked to cell damage, hormone disruption, brain toxicity, metabolic disturbance and cancer.[3]

Type of water filters

Filter jugs

Most filter jugs contain an activated carbon filter (the best type for jugs) where water passes through the filter and contaminants are absorbed in the filter, allowing purified water to pass through into the lower part of the jug. The activated carbon acts like a sponge and contaminant molecules are attracted to the carbon. They can remove chlorine, pesticides, most heavy metals, fluoride, chloramines and VOCs like benzene. Dissolved minerals, bacteria and some nitrates are not removed with carbon filters.

Certain filter jugs also include an ion exchange resin which is a material to remove further contaminants like sulphates, arsenic and nitrates. It also softens water by removing the minerals that make tap water “hard”. You will need to replace the filter every 2 – 6 months, dependent on the brand/ model and how often you’re using it. Some brands have a filter indicator that will show you when the filter needs replacing.

Counter-top filters

Counter top filters are a step up from water jug filters as they can hold much more water (as much as 25 litres) and are superior in terms of water filtration and the contaminants they remove. There are two different types: portable, free-standing, gravity-fed water filters and a countertop filter that connects direct to a tap and filters the water straight from the tap. The free-standing countertop filters come in different shapes, sizes and materials (stainless steel, plastic, glass) and need to be manually filled with tap water. They have a chamber in the top where the tap water goes and a filtration system in the middle. The purified water filters downwards into a separate chamber.

Most counter-top filters use a sophisticated activated carbon block filter with an ion exchange resin so they can remove almost all contaminants to a high-level including plastics (even toxic PCBs), pesticides/ herbicides, heavy metals (including lead which is difficult to remove), bacteria, fluoride, parasites, nitrates, nitrite, chlorine, chloramines, VOCs and pharmaceuticals. They do not remove important minerals the body needs to maintain health. The filters in counter-top models last much longer than those in filter jugs, however, most will require cleaning.  Some types of counter-top filters use a reverse osmosis system which is a more expensive option (more about this below).

Under-sink filtration systems

This type of water filter does not take up precious counter space and is more visually appealing as it fits under the sink and hooks directly up to the water mains. It includes a small separate tap that is mounted onto the sink, adjacent to the main tap. Whenever you want to dispense filtered water, you press the lever or turn the tap (dependent on the model). When water flows through the filter media, contaminants are trapped inside the filter and pure water flows out the other side through the tap.

There are different filter models of under-sink filtration systems dependent on the level of filtration you require. You can buy:

• Single-stage units – this is the most basic that uses a single filter cartridge to target a specific contaminant or group of contaminants.
• Multi-stage units – a superior system that has multiple filter cartridges (usually 2-3), each one focussing on a specific filtration stage and set of contaminants.
• Reverse Osmosis (RO) – this is a multi-stage unit with additional filtration capabilities due to its semi-permeable membrane feature.

Reverse osmosis filtration systems

The most sophisticated as they have 5 -7 stages of filtration that removes almost all contaminants dissolved in water. The downside to RO is that it can waste a lot of water and it also removes important minerals the body needs to stay healthy such as calcium and magnesium. You can re-mineralise the water using mineral drops. RO is more expensive than other types of under the sink systems; however, it is a high-quality filter that can last for many years if properly maintained. The filters need to be replaced approximately every 12 months.

Whole house filtration systems

Whole house water filtration systems are designed to filter all the water in a house by hooking into the water mains and delivering purified water to every tap. It is a sophisticated system that works in a similar fashion to (multi-stage) under the sink filtration systems in that they have multiple filter layers, each one filtering out different contaminants. Having a whole house filtration system is the ideal option but it is the costliest and involves a complex installation process.

Which water filter is best?

This will depend on your budget and household requirements. A whole house water filtration system is the best option as it guarantees pure water out of every tap so you can enjoy chemical-free showers and washed clothes that don’t smell of chlorine. This option isn’t viable for most people so the next best options are under the sink filtration systems or counter-top filters. Whichever water filter you buy, make sure you do your research and buy the best quality filter within your budget.

To learn more about environmental and household toxins, detoxication and ways to support your health naturally, take a look at the following short courses and resources:

1 https://www.sciencedirect.com/science/article/abs/pii/S0021870744901036

2 https://www.researchgate.net/publication/336532964_HEALTH_EFFECTS_OF_CHLORINATED_WATER_A_REVIEW_ARTICLE

3 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1739910/

4 https://jech.bmj.com/content/57/3/166

5 https://www.frontiersin.org/articles/10.3389/fphar.2021.643972/full#:~:text=Several%20acute%20and%20chronic%20toxic,of%20heavy%20metals%20toxic%20effects.

6 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4427717/

7 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3956646/

8 https://www.ewg.org/tapwater/contaminant.php?contamcode=1040

9 https://www.ewg.org/tapwater/contaminant.php?contamcode=1041

10 https://www.sciencedirect.com/science/article/pii/S2405844019359742

11 https://www.hsph.harvard.edu/news/hsph-in-the-news/pfas-health-risks-underestimated/

12 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4947579/

13 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7826868/

14https://www.health.harvard.edu/newsletter_article/drugs-in-the-water

15 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854718/

16 https://www.forbes.com/sites/niallmccarthy/2018/03/16/study-finds-microplastics-in-93-percent-of-bottled-water-infographic/#2ff64b973fa0

17 https://www.sciencedirect.com/science/article/abs/pii/S0048969720374039#:~:text=Microplastics%20exposure%20can%20cause%20toxicity,increased%20cancer%20risk%20in%20humans.