How does your city treat drinking water?

02/01/2020 Sidrah Ahmad

City water treatment is vital for providing a safe, drinkable supply to local populations. Utility companies have responsibility for ensuring they treat the municipal supply, so we feel confident drinking from the tap, while authorities monitor the water quality to check that potential contaminants never pose a threat to human health. Water passes through several treatment stages before it ever reaches your home — with filtration and purification getting rid of a range of pollutants, including heavy metals, organic compounds, and human-made toxins.

Your water must go through a complex system of treatment stages to remove impurities, bacteria, and parasites, and make it drinkable. Moreover, utility companies have to treat the water in such a way that it stays clean and odourless as it trickles its way into your office or home. We fill a glass from the tap, then assume it is safe enough to drink but have you ever thought about how your local water supply is treated? How much do you know about the specific processes your water passes through to make it fit for human consumption?

Why do we need water treatment?

Local water companies get their supply from surface water and groundwater, which are open to environmental contaminants and are liable to become polluted.

Surface water includes lakes, rivers, and streams. Over 70% of the public water supply in the United Kingdom come from surface water. Rainwater runoff from farms can wash nitrates and pesticides into rivers and waterways, which can find their way into the drinking water supply. Groundwater sources include aquifers and underground lakes that collect rain that has seeped through cracks and pores before the water collects in pockets between the rocks that sit deep within the ground. Utility companies tap groundwater where there isn’t enough supply of surface water to service the community.

As water trickles through rocks, it can take heavy metals like arsenic into underground aquifers. Other risks to groundwater also include agricultural runoff with authorities noting that groundwater nitrate concentrations now exceed the statutory limit allowed in drinking water. While only 14 percent of rivers in England meet the minimum “good status” standard as defined by the EU Water Framework directive indicating a decline in surface water quality as well.

The Drinking Water Inspectorate monitors drinking water quality across the UK, providing an independent overview of water supplies across England and Wales to confirm they are safe and that drinking water quality is acceptable for consumers.

How is water treated?

Water goes through a rigorous treatment process to remove any compound that could pose a threat to our health. This treatment process involves four stages that make your water ‘clean enough to drink.’

1. Coagulation and Flocculation

This uses chemicals that bind with other waterborne compounds to form larger particles, which creates a solid mass called floc.

2. Sedimentation

As floc is denser than water, it drifts to the bottom of the water treatment tank during a sedimentation process, settling in a removable layer.

3. Filtration

Once the suspended floc has been removed, the residual clear water is passed through sand, gravel, or charcoal filters that take out dissolved particles, parasites, bacteria, viruses, and toxic chemicals.

4. Disinfection

The final water treatment stage is disinfection with chlorine. This process not only removes remaining pathogens, but it keeps the water supply clean as it passes through the pipeline.

The benefits and pitfalls of water treatment

While all municipal water supplies pass through a standard treatment process, your water may undergo different levels of treatment depending on where your water comes from. For example, surface water needs a higher level of coagulation, sedimentation, and filtration than groundwater because water taken from lakes, rivers, and streams is likelier to contain more sediment and higher levels of contaminants than naturally filtered groundwater.

Every water supply also requires disinfection to guarantee the water becomes and remains safe to use. Typically, disinfection uses chlorination, chloramines, ozone, or ultraviolet light.

Chlorine is efficient at eliminating microbial pathogens, which is why chlorine is the most widely used disinfectant in the public water supply. However, some consumers don’t like the smell or taste of chlorinated water. Studies suggest bi-products of chlorine disinfection could increase the risk of cancer by up to 93%.

The risks associated with chlorine have moved utility companies to look at alternative disinfectant options. Ozonation is often to remove pathogens from the treated water supply. However, chlorine is still required as ozone cannot keep a supply contaminant-free once it has left the treatment plant.

Another disinfection option is ultraviolet light: UV from a lamp destroys viruses and bacteria.

Is water treatment always successful?

Despite the strict standards and rigorous supervision, water treatment isn’t always effective. In 2017, for example, United Utilities were fined £300,000 for failing to stop the Lancashire drinking water supply becoming contaminated with the cryptosporidium parasite. The utility company failed to detect when animal waste had seeped into an underground reservoir, subsequently contaminating the drinking water of over 700,000 people in the surrounding area and leading to an alert to boil tap water before use.

To make matters worse, the DWI Chief Inspector noted that United Utilities failed to take the appropriate action to protect consumers — even after they had discovered the contamination.

Water dispensers guarantee clean, purified drinking water

There’s only one way to ensure your water supply is entirely safe — that is, to install a filtration and purification system where you fill your glass.

A water dispenser uses an array of technologies to ensure your water supply is purified, starting with high-performance carbon filtration that removes chlorine, lead and pesticides. This is followed by microbiological purification using UV light to eliminate 99.9999% of all germs (including E. Coli, Salmonella and Hepatitis), guaranteeing pure water thanks to a process that’s 100% chemical-free.

If you’re ever unsure whether your local water supply is fit for consumption, contact Waterlogic, and our expert customer service agents will recommend the perfect point-of-use water dispenser to protect your office from water contaminants.