By Hilary Nardone, Environmental Group Training Manager
Certified ASSE 12080 Legionella Water Safety and Management Specialist
The New York City skyline is defined by skyscrapers, but have you also noticed the rooftop drinking water storage tanks as part of the iconic scenery? While they may be symbolic of the quintessential NYC landscape, these drinking water storage tanks, along with those installed inside buildings, can present public health concerns if not managed properly. Among these concerns is the risk of proliferation of harmful bacteria, including E. coli and other waterborne pathogens. Wooden tanks are more susceptible than metal ones to fouling from animals. Additionally, biofilms often grow on the inside of the tanks, allowing these harmful bacteria to multiply more easily. Rooftop towers are also susceptible to fouling from windblow debris, weather, and sunlight. To mitigate these health risks, New York City has a set of laws in place requiring that all drinking water storage tanks are both inspected and cleaned annually.
What are the annual requirements for drinking water storage tanks in New York City?
1. Annual Inspection[1],[2]
NYC Health Code Article 141, §141.07 and NYC Administration Code 17, §17-194 both specify annual inspections must be conducted for all drinking water tanks that are used to store or pressurize a building’s drinking water. The laws stipulate a physical inspection of each drinking water tank, including: assessing the condition of the internal and external tank structures, pipes, access ladders, roof, access hatches and screen; assessing the presence of pitting, scaling, blistering or chalking, rusting, corrosion and leakage, sediment, biological growth, floatable debris or insects, and rodent/bird activity in or around the tank; taking a bacteriological (coliform) sample and sending it to a New York State Environmental Laboratory Approval Program (NYS ELAP)-certified lab.
Results of the inspection must be made available to the NYC Department of Health and Mental Hygiene (NYCDOHMH) by January 15 of the following year and must be maintained by the building owner for at least 5 years.
If unsanitary conditions are found during the physical inspection, or if there are positive coliform results, steps must be taken immediately to correct the condition. Positive coliform results must be submitted to the NYCDOHMH within 24 hours. If the water quality is attributed to the sanitary condition of the tank, the tank must be cleaned and in accordance with NYC Health Code §141.09.
Violations may be issued for failure to complete an annual inspection. Inspection must be conducted by a water tank inspector who is either a licensed master plumber or works under the direct and continuing supervision of a licensed master plumber, or is a registered design professional as defined in NYC Administrative Code §28-101.5.
2. Annual Cleaning and Disinfection[2],[3],[4]
NYC Health Code §141.09 requires that drinking water storage tanks be cleaned if there is a positive bacteriological result that is attributed to the sanitary conditions of the tank per NYC Health Code Article 141, §141.07. However, the NYC Plumbing Code Chapter 6, §606.5.4.5.3 requires all water tanks to be cleaned at least once a year. These cleanings must only be completed by a person or business with a valid permit issued by the Commissioner of Health and Mental Hygiene.
When a tank is cleaned, the water supply connections to and from the tank must be disconnected or effectively plugged to prevent foreign matter from entering the distribution piping. The tank must then be drained and cleaned. Before the tank can be put back in service it must be disinfected by washing the underside of the top, the bottom, and the walls with hypochlorite solution containing at least 100 ppm free chlorine. The tank must then be filled with water while maintaining at least 10 ppm free chlorine. The chlorinated water must remain in the tank for two hours. After two hours, the tank must be drained completely before refilling for regular use.
Chlorine levels must be taken to validate that the disinfectant levels are below EPA National Primary Drinking Water Regulations. Additionally, a post-cleaning coliform sample should be taken to validate the effectiveness of the disinfection and cleaning process.
A record of the disinfection and cleaning should be kept by the owner for a least five years and made available to NYCDOHMH within 5 business days.
Barclay Water Management, Inc. proudly holds a “Building water tank cleaning, painting, and coating permit” license through NYCDOHMH and is an industry leader in cleaning and disinfecting domestic water storage tanks for waterborne pathogen control. After each cleaning, the customer will receive a Domestic Water Tank Cleaning Report, summarizing the cleaning and including before and after photos, a cleaning certificate, and the lab results from the post-cleaning coliform sample. This cleaning report should be kept onsite for at least five years and can serve as compliance documentation for the NYCDOHMH.
[1] New York City Health Code, Article 141: Water Supply Safety Standards, §141.07 Building Drinking Water Storage Tanks. https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCrules/0-0-0-46840
[2] New York City Administrative Code, Title 17: Health, §17-194 Drinking Water Tank Inspections (2013). https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCadmin/0-0-0-27907
[3] New York City Health Code, Article 141: Water Supply Safety Standards, §141.09 Building Water Tank Cleaning, Painting and Coating. https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCrules/0-0-0-46847
[4] NYC Plumbing Code, Chapter 6: Water Supply and Distribution, §606.5.4.5 Cleaning or Painting. (2014). https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCrules/0-0-0-46847