Domestic Water Sterilization

To obtain occupancy permits for new buildings, as well as for additions or reworking of water systems in existing buildings, builders must prove to inspectors that the water is safe to drink. The industry refers to the piping that supplies potable water as the domestic water system. The domestic water system must be thoroughly cleaned and the water needs to be tested and proven safe to drink, before the building can be occupied.

The cleaning and testing should be done by an independent party to achieve full safety certification, and Arc Water Treatment is particularly qualified to perform this task. Similar to independent certification of elevators and sprinkler systems, the safety of the water piped to each drinking fountain, coffee machine, and sink is paramount to ensuring tenants that a building may be safely occupied.

Arc Water Treatment offers to sterilize and certify the safety of the domestic water systems, and does this daily for Mechanical and Plumbing Contractors. Our Service Technicians are all fully Certified by the State of Maryland to take water samples, and handle them properly for analysis by an independent laboratory, which is also fully certified to assess the safety of the water for drinking purposes.

The procedure involves injecting a strong solution of chlorine into the new piping at the source, and ensuring the chlorine reaches every fixture on the system. Our highly trained Technicians have test chemicals to verify the chlorine will sterilize all parts of the domestic water system, and must remain in contact of all parts for at least three hours, as prescribed by the American Water Works Association C651 Plumbing Code. They then fully flush the system, testing again at every fixture to ensure only city water remains in the system. After flushing, a sample of the water is taken, treated with a Thiosulfate pill to ensure test validity, sealed and documented for the lab with a chain of custody form.

The independent laboratory tests this certified sample primarily for the presence of fecal coliforms, and provides a Certificate of Analysis to document whether the sample is within EPA standards for drinking water. Arc Water Treatment then forwards the results, stamped with the seal of our Professional Engineer, to the contractor who needs this independent certification that the water is safe to drink, often as the final step to obtaining the occupancy permit.

Disinfecting Domestic Water Lines

The plumbing system for every new building, and any renovation affecting the domestic water system, must be cleaned and disinfected before the building may be occupied. This procedure, often called Sterilization, is a matter of law today as incorporated in many building codes, and has been practiced by the building trades for over 50 years. The standards are set by the American Water Works Association’s International Plumbing Code, as published in their handbook Water Chlorination Principles and Practices, and they have provided the language accepted in local government plumbing codes.

Chlorine is used as the primary disinfectant chemical to “destroy or inactivate microorganisms of sanitary significance” before the water can be used for domestic consumption. This use of chlorine as a disinfectant dates back to before 1920 and is actively used in municipal water treatment systems as well as a method for sterilizing newly constructed plumbing systems. Chlorine can be used in a variety of forms and depending upon the application, it may be applied as liquid chlorine, gaseous chlorine, or crystallized hypochlorite. When chlorinating new piping, the standard requires that a slug of water be dosed with chlorine to a concentration of 200 mg/L (parts per million), and that all areas of the system, including every faucet, drinking fountain, shower head and toilet, be exposed to the highly chlorinated water for at least three hours. The system then must be thoroughly flushed and tested at every fixture to ensure the chlorine is purged from the domestic water.

The disinfection procedure further calls for samples of the water to be taken and examined by a qualified laboratory, after the water lines have been flushed. These samples are carefully kept under controlled temperature, and then are tested for the presence of coliform and E. coli bacteria. The lab results must demonstrate that less than 1.1 coliforms per 100 ml were in the sample or else the piping has to be disinfected again until a sample shows that it is below this level to prove that it is free of bacteria and safe to drink.

Arc Water Treatment is a specialist in the practice of disinfecting domestic water lines. All of our trained Service Technicians have taken the Maryland Water Public Drinking Water Sampler Seminar conducted by the Water Supply Program of the Maryland Department of the Environment. They have passed the Sampler Exam and are considered Certified Samplers for purposes of taking water samples and handling them properly to labs for certification that the water is safe to drink. In conjunction with our certified lab, we provide a chain of custody form that proves the sample was handled properly. Then together we provide a Certificate of Analysis, sealed by a Professional Chemical Engineer, that indicates “the water is suitable for drinking and sanitary purposes, indicating that the sterilization was satisfactorily completed”.

Arc Water Treatment is often contracted for the domestic water system sterilization, separate from our contract for HVAC water treatment equipment and service. Many construction and most remodeling projects don’t have new water treatment requirements, yet involve changes to the domestic water piping. This necessitates the disinfection of those pipes, and the plumbers will ask us to do the work, and obtain the independent certification necessary for an occupancy permit. While these can often be accomplished with one or two Service Technicians, we can take on the largest jobs where teams of Technicians work together to ensure all fixtures are disinfected. Some of the notable jobs we have done recently include several buildings on the campus of the National Institutes of Health, the numerous highly secured buildings for the Department of Homeland Security, and offices in the 1st Mariner Bank Headquarters, the new landmark building on the eastern side of Baltimore Harbor.