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. 82% of the public water supply in Ireland comes 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. Tests have also identified excessive levels of highly toxic metals like lead in local drinking water supplies. A local authority in Coolock, north Dublin, found lead contamination at 12x the legal limit in 2018 — while Sutton Dart in north Co. Dublin has lead concentrations as much as 15 times the legal limit. Yet, these are just two of the 30 areas across the country that have reported unsafe levels of lead in drinking water in the last two years.
In Ireland, the Environmental Protection Agency supervises the quality of the public water supply, while Irish Water has responsibility for ensuring the national supply complies with acceptable standards. In the event of contamination, Irish Water must inform the EPA, though it’s up to the local authority to prepare plans to address any problem with contamination, which the EPA must then approve.
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.’
This uses chemicals that bind with other waterborne compounds to form larger particles, which creates a solid mass called floc.
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.
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.
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.
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. The European Commission has opened a case against Ireland as Irish Water has failed to reduce the levels of trihalomethane — a bi-product created when using chlorine to disinfect water — with THM contamination exceeding limits across the country.
Irish Water has already received a €6,000 fine for failing to reduce the levels of THMs at six separate water treatment plants, and the issue remains largely unresolved.
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.