Access to safe, clean water is a luxury that is often taken for granted. Because immediate access to water is available in virtually every modern building, many people forget just how complicated the water treatment and distribution process can be. In addition, many people also fail to realize how dangerous water can be to consumers if it becomes contaminated at any point during this process. After exiting a treatment plant, water spends the majority of its time in the distribution system of the facility where it will eventually be consumed. Thus, in order to prevent contamination and protect public health, clean water distribution systems are essential.
Understanding the Need for Maintenance
In order to be safe for human consumption or use, water must meet certain standards. In most cases, water meets these standards when it leaves the treatment plant. However, if the water distribution system it enters has not been properly cleaned or maintained, the water may decrease in quality before it reaches the consumer. Dirty distribution systems have a high potential for scaling, as well as biofilm formation. This can lead to the following water-related issues:
- Low chlorine residuals
- Taste and odor changes
- Unsafe levels of disinfectant by-products
- Discoloration or visible dirt
- Proliferation of waterborne pathogens
Perhaps the most worrisome of these problems is the proliferation of pathogens, such as Legionella pneumophila. These bacteria can cause serious illnesses in humans. Fortunately, all of the problems above, including the growth of bacteria, can be effectively avoided through proper maintenance and cleaning protocols.
Water Distribution System Maintenance Tips
To improve the quality of water and protect the health of consumers, facilities should follow the tips below.
1. Inspect/monitor source water.
Understanding the characteristics of the water that enters a distribution system allows personnel to plan treatment efforts based on the events that are most likely to occur within the system. Facilities should examine the makeup of the source water to gain insight about the water’s potential for:
- Biological growth
- Scaling
- Corrosion
- Generation of disinfectant byproducts
Inspections should be performed on a regular basis and any time the source water quality changes.
2. Choose the right technique.
A variety of water distribution system cleaning techniques are available. These techniques include:
Mechanical Cleaning:
Mechanical cleaning methods utilize various tools to scrape the interior surfaces of the water mains with the goal of removing scale and other unwanted materials. In order to clean a water distribution system mechanically, the portion of the system being cleaned must be taken offline. Sediment disposal and excavation are also required.
Pigging and Swabbing:
Pigging and swabbing is a method of pipe cleaning that employs small pieces of polyurethane propelled by water. These polyurethane fragments, which are known as “pigs,” can effectively remove biofilm, sediment and scale. As with mechanical cleaning, pigging and swabbing can only be performed on pipes that are offline.
Main Flushing:
Main flushing is the most common method used to maintain water distribution systems. During main flushing, a high pressure flow of water moves through the pipes in order to remove debris, increase chlorine residuals and reduce disinfectant byproducts. Two primary types of flushing exist: conventional flushing and unidirectional flushing. While conventional flushing utilizes all available flow pathways, unidirectional flushing isolates flow and reverses its normal pattern. Because flow rates decrease as distance from the flushing hydrant increases, conventional flushing isn’t an effective method for removing biofilm or sediment. Unidirectional flushing, on the other hand, provides better results.
Chemical Cleaning:
Chemical cleaning methods involve the use of chemicals to remove sediment, loosen biofilms and improve water quality. Depending on the chemicals utilized, treatments can be used to increase the effectiveness of mechanical cleaning methods, or they can be used on their own. When the proper chemicals are applied, these methods can be very effective at eliminating pathogens. In some cases, chemical cleaning methods can even be used to clean pipes that remain online.
Sources
Photo credit: zayzayem / Foter / CC BY-SA
Photo credit: Sacca / Foter / CC BY-SA
https://blueearthproducts.com/wp-content/uploads/2014/08/Blue-Earth-January-2014.pdf
