It is the preferred method for most municipal water utilities in all regions of the world. Where it is used, it has played a crucial role in the eradication of waterborne diseases such as cholera, typhoid, and dysentery.
The nearly universal application of this method is attributable to the following factors:
Chlorine in drinking water is safe for consumption. The small amount of chlorine typically used to disinfect water poses no risk to human health. The World Health Organization (WHO) has established a guideline value of 5 mg/l (ppm) for chlorine in drinking water, meaning that such concentrations are considered acceptable for lifelong human consumption.
Chlorine is a residual disinfectant. This means that, when the process is carried out correctly, chlorine’s disinfecting properties—and thus the protection it provides—are present wherever the water is found. This distinguishes chlorine from non-residual disinfection methods such as UV and ozone. These disinfection methods do not “travel” with the water and therefore have significant limitations.
However, it has been documented that the use of chlorine as a disinfectant can have drawbacks in the offshore/maritime sector, and these are worth noting.
It is true that if the source water has a high organic load and is consistently over-chlorinated, the risk of hazardous byproduct formation increases. Although some of these byproducts are carcinogenic, this should not automatically deter users from using chlorine as a disinfectant. Only under exceptional circumstances would the water in the offshore sector contain a sufficient organic load to pose a risk of carcinogenic byproducts. OWM has never encountered such circumstances.
There are known water sources where the organic load is high, such as in Norway, but even in such cases, an appropriate risk assessment and the right control measures can ensure that chlorine remains the safe and effective disinfectant of choice. However, if a decision is made to forego residual disinfection, users must carefully consider how this might affect control measures. In these cases, users must still be able to demonstrate how the water is managed and maintained throughout the entire system without compromising control.
When prioritizing risks, the following statement from the WHO (World Health Organization) should be taken into account:
“The health risks from byproducts that may be present in drinking water are extremely small compared to the risks associated with inadequate disinfection. It is therefore important that disinfection is not compromised in efforts to control such byproducts.”
Sensitivity to the taste and odor of chlorine is an aesthetic issue and should never take precedence over health and safety considerations. Sensitivity to the taste and odor of chlorine in water is primarily determined by two factors: what a person is accustomed to and the chlorine concentrations in a water system.
If a person is accustomed to drinking water that does not contain chlorine, concentrations at the upper limit of the control values (0.2 ppm–0.5 ppm) or slightly above may be detectable. If concentrations are consistently higher than the control levels and continue to rise, eventually everyone will perceive chlorine as a taste, odor, or both. (In both cases, there is no health risk as long as chlorine concentrations remain below 5.0 ppm—that is, ten times the control level.) To reduce complaints about taste and odor, the chlorine supply must be kept within the control levels. The proper selection and use of chlorine dosing equipment ensure that this is always the case.
The primary goal of disinfection in all public and private water systems is the elimination of pathogens responsible for waterborne diseases. OWM is an independent provider of all services and support in the field of water management, and we recommend the use of chlorine as a safe and reliable solution for this purpose.
Whether it’s monitoring, permitting, quality control, or complex environmental issues, together we provide reliable insights you can rely on with confidence.
As a global leader in fully integrated water management services for the oil and gas and maritime sectors, we often find that our clients are simply looking for a hassle-free way to comply with drinking water regulations.
At most facilities, the company physician is responsible for the daily monitoring of water quality, with checking water quality being part of his or her duties. In the past, this meant that water samples were routinely sent to onshore laboratories, which naturally had to be coordinated with the helicopter’s flight schedule. At many locations, this limits sampling to two specific days per week. In cases where urgent testing is needed outside these times, a costly special helicopter flight must be arranged; otherwise, the samples will be delayed. With this approach, the quality of the results depends entirely on the care and accuracy of the sampling process, as well as on the variable handling and logistics involved in transporting the samples to the testing site.
Normec OWM offers consultation, analysis, advice, products, and operational execution to create a comprehensive water management service with the expertise needed to ensure the client’s complete confidence. With extensive experience in managing drinking water systems during the reactivation of drilling platforms, Normec OWM is highly skilled at overcoming the typical risks associated with such projects.
