Chlorinating/Disinfecting Potable Water Mains

Potable water main chlorination/disinfection is a process used in water pipelines to kill and remove harmful bacteria, especially coliform bacteria as confirmed by laboratory analysis. The goal of this process is to kill waterborne pathogens that could cause a disease outbreak. A chlorine solution using sodium hypochlorite is injected into the water mains to oxidize microbiological material, organic, and inorganic compounds. It is necessary for health and safety reasons and required by government rules and regulations that potable water mains be chlorinated/disinfected:

• Prior to newly constructed potable water mains being put into service
• Prior to existing potable water mains being put into service after being removed from a water distribution system for maintenance and repair
• When water mains have tested positive for coliform bacteria

Matt-Chlor strictly uses and follows the chlorination/disinfection methods as detailed in job specifications and in accordance with A.W.W.A. Standards.

Chlorinating/ Disinfecting of Potable
Water Systems in Buildings

All new, remodeled, or repaired potable plumbing water systems in commercial buildings must be chlorinated/disinfected to kill bacteria. The method used and followed depends upon the job requirements and job specifications.

Chlorinating/Disinfecting Water Storage Facilities

Humans have always needed the ability to store potable water before it is distributed. Today, such facilities come in various forms and sizes such as:

• Reservoirs
• Tanks
• Towers

Each one provides storage of disinfected water before it is distributed for domestic use, emergency use such as fire fighting, commercial water and wastewater use, and industrial water and wastewater use. When contamination occurs, a water storage facility must be chlorinated/disinfected. Chlorination/disinfection is required:

• Prior to a newly constructed water storage facility being put into service
• Prior to using an existing water storage facility that has been entered into for inspection or maintenance
• When a reservoir has tested positive for coliform bacteria

Chlorinating/Disinfecting of Wells

Water from private wells provides safe water for about 40 million Americans each day. A contaminated water well sample does not necessarily mean that the whole aquifer is contaminated but contaminated aquifers are usually difficult to clean up to drinking water standards. When contamination does occur, the well must be chlorinated/disinfected by using a process which injects a chlorine solution to kill bacteria and microorganisms into the well casing, the pump and associated piping, the gravel pack, and the immediate area of the aquifer around the casing. In addition, water samples must be collected and processed for verification of satisfactory bacteriological quality of water.

Wells are chlorinated/disinfectd:

• Prior to using a new well for potable water service
• Prior to using an existing well that may have been contaminated during maintenance, service, construction, flood, etc.
• When a well has tested positive for coliform bacteria

De-Chlorination

Disposing of heavily chlorinated water into the environment such as storm drains or waterways can cause damage and is regulated. De-chlorination is a process of partially or totally removing chlorine from the water by adding chemicals to the discharged water to neutralize the chlorine.

Flushing of Chlorinated Water

After the heavily chlorinated water has remained in the water mains for the required amount of retention time, the chlorinated water must be removed from the pipelines. All main fittings, valves and branches must be flushed. Regulations require that the chlorine residual levels leaving the water main are no higher than the normal level in the water distribution system or that is acceptable for domestic use.

Water Sample Collection and Bacteriological Laboratory Testing and Reports

The bacteriological testing of water is critical as it determines the presence of waterborne pathogens and human waste in water. The water sample is tested for coliform bacteria which is present in human feces (fecal coliform bacteria) and in soil contaminated by human waste (nonfecal coliform). Total coliform is a group made of the fecal coliforms and the nonfecal coliforms. At times, a heterotrophic or standard plate count (HPC) test is required which tests the total count of almost all types of bacteria in the water sample. The testing process begins by properly collecting water samples using laboratory provided sterile bottles. It is critical that contamination is avoided. The number of samples and the location of the grab(s) vary. There are four testing techniques; the most common is the presence-absence technique. Only laboratories that are certified by the EPA or the state can be used for analyzing drinking water sample compliance.

pH Controlling of Discharged Water

pH is the measurement of acidity in water and is normally affected by factors such as chlorine, carbon dioxide, mineral acids, and heavy metal salts. In general, the lower the pH, the higher the acidity, and the higher the rate of corrosion. At times, chlorinated water remains stationary for a period of time in the water mains which can affect the pH, either making it too high or too low, which can stress and kill aquatic organisms and fish if released into the environment untreated. The pH must be adjusted by mixing chemicals to the discharged water to protect the environment from such damage. This process is called pH neutralization.

Hydrostatic Testing of Pipelines:

Hydrostatic testing of pipelines is a test method to find leaks and to test the strength of the pipelines by pressuring them beyond their maximum operating pressure. The purpose of testing is to eliminate any defect that might threaten its ability to sustain its maximum operating pressure. After a test, a pipeline can be expected to safely contain its intended operating pressure.

Fire Hydrant Flow Testing

Fire hydrants are an integral part of all water supply distribution systems. Regular testing of fire hydrants is necessary to guarantee they are capable of delivering water at the proper flow rate and pressure in the event of an emergency. Water main and hydrant flow capabilities impact important decisions that affect public safety. Regular fire hydrant flow testing can reveal problems with the valves. Such problems arise because a water system is always being affected by improvements, deterioration, changes in usage, and even water district maintenance activities.