In the modern world the availability of clean drinking water is a major backbone of our civilisation. We hardly think about what happens when we turn on a tap in our home and have an unlimited supply of clean and safe drinking water.
However, despite the availability of clean water there are still issues with the public water supply, in the US there are, on average, almost 7,000 boil water notices which is when water companies require water to be boiled before it can be safely drunk due to problems with the supply which cause it to become unsafe to drink. Additionally there are notable issues where the water supply has been contaminated and potentially poses a risk to those who drink it.
History of Public Water Treatment
Water treatment in various forms goes back a very long time with the ancient Greeks and Egyptians filtering and boiling water or using alum to remove suspended particles by 1500 BC. Most cultures looked to source water from untainted sources, hence the Roman aqueducts which brought water from outside cities such as Rome.
In London during the 17th century the New River was constructed, it was deliberately designed to be slow flowing to increase sedimentation and was screened along its route to catch weeds and debris.
One of the major drivers for improved water treatment was the introduction of the water closet (toilet) which used an increased flow of water to flush away waste, before this time cesspits were mostly used for solid waste, however the additional water caused the pits to overflow and contaminate rivers and other water sources leading to disease. To illustrate the situation, in Chicago the use of water per head increased from 33 gallons to over 144 gallons in less than thirty years.
An increase in the awareness of the transmission of diseases such as cholera, typhoid and yellow fever in the 19th century manifested in a growing need to filter and treat municipal drinking water. The growth of cities and the contamination of nearby water sources by sewage and industrial waste led to an increasing demand for improved water treatment.
The understanding of the spread of disease was still basic at this time with many scientists still feeling that diseases such as cholera were transmitted by foul smells. It was the scientist John Snow who used early data modelling to show that cholera was passed by water, he was able in 1854 to prove that a cholera outbreak in London could be traced to a single well on Broad Street.
Following this, in Lowell, MA after a typhoid outbreak in 1890, William Thompson Sedgwick applied bacteriological methods to the investigation and was able to establish a link between contaminated water and the disease.
Effective water treatment as opposed to simple filtration to remove solids began to be used in the early 20th century. In 1902 Jersey City became the first city in the US to use chlorination to improve water safety. However there were some who still doubted that chemical treatment was required, this case was made clear with an incident in 1916.
On January 14, 1916, the chlorination equipment in Milwaukee, Wisconsin, ceased functioning for 7 hours. In that time the water pumped from Lake Michigan caused 25,000 to 100,000 cases of diarrhea as well as 500 cases of typhoid fever, with 60 deaths. By this point the need for treatment was becoming clear. 1
Modern Water Treatment
Modern water treatment is made up of a number of processes, some are different in certain areas.
- Pre-chlorination – chlorine is used to kill bacteria and algae in the water prior to filtration.
- Aeration – air is blown through the water to remove dissolved iron and manganese.
- Coagulation – chemicals such as aluminium sulfate are added to the water which causes dissolved solids such as silt, clay or organic solids to flock together in clumps which can then be more easily removed using sedimentation and filtration.
- Sedimentation – the water is allowed to stand in vats so that the flocked solids sink to the bottom of the vat and can be removed.
- Filtration – to remove any remaining particles from water, it can be filtered using sand beds or activated charcoal.
- Disinfection – for killing bacteria, viruses and other pathogens Chlorine or Ozone may be used as a disinfecting agent’. Alternatively ultra-violet light may be used.
- Once water has been treated it is stored in sealed reservoirs before being pumped through the pipe network to your home.
Potential Issues With Water Treatment
Water treatment is very strictly controlled and the output is regularly monitored to ensure it is safe and within acceptable standards. However there are some potential concerns with the use of chemicals as part of the treatment process.
For example, chlorine reacts with natural organic compounds in water to form potentially harmful chemical by-products. These by-products, trihalomethanes (THMs) and haloacetic acids (HAAs), are both carcinogenic in large quantities and are regulated by the United States Environmental Protection Agency (EPA).
There are fewer by-products created when using ozonation, however, it has been discovered that ozone reacts with bromide ions in water to produce concentrations of the suspected carcinogen bromate. Bromide can be found in fresh water supplies in sufficient concentrations to produce (after ozonation) more than 10 parts per billion (ppb) of bromate — the maximum contaminant level established by the USEPA. 2
Breakdown of Water Treatment Process
As with any process there can be times when the process is compromised, this is when your local water company will issue a ‘Boil Water Notice’. Issued when there are unacceptable levels of bacteria or viruses in the water, or there are unacceptable levels of cloudiness.
A boil water notice can be caused by a number of reasons, for example a broken or leaking water main is the cause of over half of the notices being issued with confirmed microbial contamination leading to almost 14%.3.
Boil Water Notices
When there is an issue with your water supply it can be impossible to tell as your tap water may look and taste the same but could contain microscopic contamination such as bacteria or viruses. When an issue has been identified by the water company you will be advised to heat the water to a rolling boil for at least one minute to ensure that it is safe to consume. 4
Not everyone understands or reacts correctly to a notice when it is delivered, almost half the people who receive a boil water notice (48.3%) will ignore the advice. 5 Even when people were aware of the requirement to boil water 87% engaged in behaviour which is likely to increase the risk of infection such as forgetting to boil water to brush teeth (54%) or preparing food with unboiled water (17%). 6
Therefore, even if you are very careful it is possible to put yourself or your family at risk either by missing a boil water notice or to fail to follow the instructions due to force of habit. Additionally, there is likely to be a time before the boil water notice can be effectively distributed when you may be at risk due to an unsafe water supply.
Issues With Water Supply
Across the USA there are a number of potential issues which can occur with water supplies, these include:
- Heavy metals such as lead or arsenic – heavy metals are naturally occurring and cannot be destroyed but can also enter the water supply via pollution or lead pipework. Heavy metals are dangerous as they accumulate in your body and cause health risks ranging from lead poisoning to potential cancer risks.
- Nitrates can get into the supply from fertilizers and farm runoff and can cause methemoglobinemia in infants.
Haloacetic acids (HAAs) are a byproduct of drinking water chlorination and may cause irritation to the eyes and skin and it may cause cancer.
- There is evidence that there are issues with water across America. The EPA has stated that there are 41 states which have reported higher than acceptable levels of lead in drinking water. The American Society of Civil Engineers believe that there is an $80 Billion investment required to resolve issues with water infrastructure which, in places is over 150 years old. 7
Water Crisis in Flint
The most recent issue related to water supply in the US is the ongoing crisis in Flint, Michigan.
The water supply in Flint was changed in April 2014 from treated Detroit Water and Sewerage Department water sourced from Lake Huron as well as the Detroit River to water sourced from the Flint River. It is reported that corrosion inhibitors were not applied which caused lead from aging pipes to leach into the water supply. It has been found that there are 29,100 ageing lead pipes which need to be replaced within the Flint water system.8
Lead was used in the early 20th century to connect household supplies from the cast iron mains supplies as it was easy to work and relatively inexpensive. It was since discovered that lead pipework can leach lead into the water supply especially if there are certainly contaminants in the supply. The previous supply source had been treated to maintain the lead levels in the water to an acceptable level, however the new supply was not treated to the same level.
It has been stated that no blood-lead level is considered completely safe. Children under five especially infants and unborn children, bear the greatest risk of ‘deleterious and irreversible health outcomes’.9
In Flint, between 6,000 and 12,000 children have been exposed to drinking water with high levels of lead and they may experience a range of serious health problems. 10 The water change is also a possible cause of an outbreak of Legionnaires’ disease in the county that has killed 10 people and affected another 77. 11
It is not known at this stage the eventual cost of this incident or what the longterm effects will be for those affected.
Ensuring You Are Safe
To reduce the risk of water based contamination you should ensure that, if you do receive a boil water notice that you ensure everyone is aware what is required and that you boil water for every use, including brushing teeth and preparing food.
An alternative is to use your own secondary water filter system within your home. These systems utilize carbon filtration medium as well as ultra-violet light, together this will remove heavy metals such as lead, solids and chemicals such as chlorine as well as killing any bacteria or viruses in your water supply. It is a way of ensuring that you and your family remain safe whatever may happen to the municipal water supply.
These cost effective products can be easily installed within your house and provide additional peace of mind as well as improved flavour and odour.
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