When it comes to potable mains drinking water the most important threat for humans are pathogens that exist in the drinking water. They can enter the body as we drink the water and can lead to a variety of diseases, some of which can be life threatening.
A lot of drinking water is treated with disinfectants at source by the water company to ensure that it remains safe for drinking. However, once it leaves the water treatment plant no further disinfectant is added and as such the distribution network must be kept clean and bacteria free in order for the drinking water to reach the end person safely.
Any new pipe, repairs or refurbishment pipe work related to the current mains supply network needs to be clean and contaminant free to ensure cleanliness of the present network. If contaminated water line is added to the present network it has the potential to contaminate the entire system, potentially triggering illness in a whole bunch of people.
As such all new pipe work must be disinfected before use. The principle of this process is to introduce chlorine into drinking water, the most common chlorine releasing substance being sodium hypochlorite. Once this is added to drinking water chlorine is released and this chlorine is a strong oxidant which can rapidly kill all living cells. The procedure utilised for new water pipe is termed chlorination and utilises this chlorine at 50 ppm in place for a minimum of 1 hour to destroy all unsafe bacteria. The system is afterwards flushed through with fresh water and sealed to prevent additional ingress of bacteria and dirt.
Any provider carrying out work such as a new mains chlorination should have the appropriate health and safety training and all operatives must hold the Blue Water Hygiene Card. This is a training program created for operatives working on potable water supplies to make certain they are acquainted with the issues of contamination and the risks involved.
All work carried out should supply a chlorination certificate from the company carrying out the job and this must include such information as date, pipe size and volume, chlorine level, contact time and final chlorine level after flushing. Microbiological evaluation of the drinking water inside of the chlorinated water line should also be carried out to make sure that no bacterial contamination of the water line remains.
Once the chlorination procedure has been carried out and the microbiological analysis has come back clean the new water line may be connected onto the mains network.
