The Safe Drinking Water Act (SDWA) was passed by Congress in 1974 to protect public health by regulating the nation’s public drinking water supplies.  Under the SDWA, the Federal Environmental Protection Agency (EPA) sets standards for drinking water quality and with its partners implements various technical and financial programs to ensure drinking water safety.

Millions of Americans receive high quality drinking water every day from their public water systems. However, the water that is being consumed within the premises, at the tap, should not be taken for granted, since it may not be safe to drink.

The water that is consumed within the home, places of business, schools, public buildings, medical facilities or any building that receives drinking water from a public water system may be compromised by the piping arrangements within said building.

The responsibility for assuring that public water systems deliver safe drinking water to the user falls under the jurisdiction of state drinking water programs and/or the EPA.  The States acting as a primacy agent, require public water systems to meet the primary standards as specified by the National Primary Drinking Water Regulations (NPDWR). These primary standards protect public health by establishing enforceable maximum contaminant levels which limits the concentration of contaminants in drinking water.  The term ‘‘maximum contaminant level’’ as stated in SUBCHAPTER XII—SAFETY OF PUBLIC WATER SYSTEMS PART A—DEFINITIONS §300f. Means the maximum permissible level of a contaminant in water which is delivered to any user of a public water system.  (Note, the term “delivered to any user of a public water system.” It does not state the consumption of water at the tap.)

Pursuant to the NPDWR, public drinking water systems must meet health-based federal standards for contaminants, including performing regular monitoring and reporting. The water delivered to the user at the service connection before the meter shall be in compliance with the established NPDWR standards.

But what about the water that is consumed within the building!

The water consumed within the building should also be in compliance with the primary standards but due to the presence of unprotected cross-connection, the water that is consumed within the building may be compromised by unprotected plumbing cross-connections that exists within the internal plumbing system.

The presence of an unprotected cross connection represents a loss of physical integrity in a distribution system through which backflow of contaminants can occur (NRC, 2006).

These unprotected cross-connections may cause and represent a significant public health risk (US EPA, 2000b) by allowing chemical and biological contaminants into the potable water supply (a conclusion of the Microbial/Disinfection Byproducts Federal Advisory Committee (M/DBP FACA)).

The Cross-Connection Control Manual, United States Environmental Protection Agency, Office of Ground Water and Drinking Water, 2003 states “Plumbing cross-connections, which are defined as actual or potential connections between a potable and non-potable water supply, constitute a serious public health hazard.”

Is the water consumed within a building at the last free flowing tap safe to drink? Not necessarily!

The NPDWR and some state drinking water programs do not address public health issues resulting from the internal plumbing system that conveys potable water from the service line to free-flowing taps within the building. The issues associated with the internal plumbing system are considered by some public water systems to fall outside the scope of responsibility. The public water systems recognize the unique characteristics of premise plumbing and the public health risk of the drinking water at the tap but refer this matter to the building owners, code enforcers and consumers to minimize the risks.

Section 602 of the International Plumbing Code states, “Every structure equipped with plumbing fixtures and utilized for human occupancy or habitation shall be provided with a potable water supply ….” and “.… potable water shall be supplied to all plumbing fixtures.”

Section 608 of the International Plumbing Code sates “A potable water supply system shall be designed, installed and maintained in such a manner so as to prevent contamination from non-potable liquids, solids, or gases being introduced into the potable water supply through cross-connections….”

The Uniform Plumbing Code contains similar language. Section 601.2 sates “ Each plumbing fixture shall be provided with an adequate supply of potable running water piped thereto in an approved manner, so arranged as flush and keep it in a clean and sanitary condition without the danger of backflow or cross-connection”

If the public water system delivers water to a building or facility as prescribed by the NPDWR and the internal water supply system is designed according to the plumbing codes, the water that is consumed within a building does not constitute a public health hazard.

However, this is not always the case, because in some areas of the country, the plumbing code as it relates to cross-connection control and some drinking water cross-connection control programs are ineffectively enforced.  While there are cross connection control programs in place in many locales, many others lack such programs.  There is evidence that inconsistent implementation of such control programs can result in public health risk (NRC, 2006).

If the public water system feels that the implementation or enforcement of the plumbing code is not adequate to protect the public water system from the hazards associated with internal plumbing cross-connections, the public water system shall act to protect the public water system.

If there are unprotected cross-connections within a building, the public water system and consumers of water could be at risk, if certain hydraulic conditions were to occur within the public water system or internal plumbing system that could cause backflow to occur.

To protect the water in the public water distribution system, some public water systems are requiring the facility owner to install a backflow prevention device at the service connection as a requirement of receiving water.  In some cases, this is a public water system policy, in other situations, the public water system may be mandated by state regulations to require the installation of the backflow prevention device on the service line.

It should be noted; the installation of this backflow prevention device does not control cross-connections within the building. If unprotected cross-connection exists within the internal plumbing system, individuals consuming water within the building may still be at risk despite the installation of a backflow prevention device on the service line.

If there is still a risk of consuming non-potable water within a building, what is the purpose of a backflow prevention device on the service line?

The backflow prevention device installed on the service line should be considered a “service line protection device” that prevents the backflow of potable water into the public water system. The service line protection device should not be acknowledged as a cross-connection control measure because if it was recognized as such, the water downstream of the backflow prevention device would be considered non-potable.

By definition of a cross-connection, the water downstream of the backflow prevention device would be labeled as non-potable. If the service line backflow prevention device was installed for cross-connection control this would be in direct conflict with the plumbing codes. As stated in the plumbing code only potable water can be supplied to plumbing fixtures.

The installation of a backflow prevention device on the service line should not be considered a comprehensive cross-connection control program because it does not control cross-connections that may exists within the internal plumbing system. The installation of a backflow prevention device on a service line should be considered a peripheral part of a cross-connection control program.

So, what is cross-connection control and how can the public water system implement a cross-connection control program without coming into conflict with the plumbing code and ensuring the quality of water to the last free flowing tap.

If the facility is in compliance with the plumbing code with respect to cross-connection control, the consumers of water within the building and the public water system would not be at risk. A backflow prevention device on the service line would not be necessary, unless mandated by state drinking water regulations. The threats of a cross-connection incident are removed by controlling the cross-connections where they are found. Compliance with the plumbing code is all that should be necessary.

As a supplement to the plumbing code, the installation of a backflow prevention device such as a double check valve assembly or residential dual check valve can be installed as a service line protection device to prevent backflow of potable water into the public water system.

It should not be misconstrued that the facility is in compliance with the plumbing code by the installation of a backflow prevention device on the service line.  The installation of this service line backflow protection device does not relieve the public water system’s responsibility of informing the building owner of their responsibility to comply with the plumbing code as it relates to cross-connections.

How does the public water system know that the facility is in compliance with the plumbing code?

As stated in the EPA Cross-Connection Manual, …”in order for the supplier of water to provide maximum protection of the water distribution system, consideration should be given to requiring the owner of a premise (commercial, industrial, or residential) to provide …. adequate proof that the internal water system complies with the local or state plumbing code(s).” Compliance with the plumbing code as it relates to cross-connections is the responsibility of the owner of the building and the plumbing code officials. The public water system responsibility is to notify the owner of the concerns and issues relating to cross-connection control.

A public water system cross-connection control program requires the assistance of the plumbing industry. The strict enforcement and implementation of the plumbing code needs to take place.

The public water system cannot state that the tap water is safe to drink unless cross-connections are controlled where they exist. The consumers of water should be made aware that the installation of a backflow prevention device on the service line is a service line protection device meant to protect the public water distribution system. It is not meant to protect the consumers of water from a cross-connection incident which may occur within the building nor does it provide them with tap water that is safe to drink.

To protect the public health against the dangers associated with cross-connections, both the public water system and the plumbing industry must understand their roles and responsibilities so that they can be clearly related to the building owners and consumers of water. Failure to take actions is compromising the welfare of the water consumers and is misrepresenting the quality of water that is delivered to the last free flowing tap.

State drinking water program officials need to take actions regarding the issues related to cross-connections so that building owners and consumers are aware of the concerns.  Cross-connection control is a public health concern and the consumer of water should be given a certainty that the tap water is safe to drink.

Redrafting state cross-connection regulation to reflect the issues associated with controlling cross-connections should take place as well as providing staff to implement a comprehensive cross-connection control program that addresses the quality of water at the last free flowing tap.

If the public water system requires the installation of a backflow prevention device on the service line, the building owner or representative should be made known that the installation is for hydraulic purposes only and not for cross-connection control. The public water system should also inform the facility owner that there are risks associated with the installation of the backflow prevention on the service line such as but not limited to thermal expansion issues, pressure losses or other hydraulic issues, flooding concerns, vandalism and security concerns.

To apprise the consumers of water, the public water system in conjunction with the plumbing code officials should require each facility to place a certificate of compliance in a prominent location within the building, indicating that the internal plumbing is in compliance with the plumbing code as it relates to cross-connection control.

To protect the consumer of water within a building, cross-connections should be control where they exist, and if mandated, a backflow prevention device should be installed on service lines to protect the public water system against backflow.

So, is tap water safe to drink?

About the Author

James Holeva has over forty years of experience in the environmental management field. He retired from the Massachusetts Department of Environmental Protection in 2003. His experience includes, drafting drinking water regulations and policies, chairing a board of certification for drinking water operators, managing the day-to-day operations of a drinking water supply watershed system, managing a state regional drinking water regulatory program that included enforcing federal and state regulations, and managing the day-to-day operations of a public works department. In alliance with NEWWA he has conducted numerous cross-connection control trainings throughout the New England States, NY, NJ and PA.  In addition to conducting cross-connection control training, he taught environmental science courses at the college level and developed training programs for the water works industry and others. He served as the treasurer of a national certification association and was instrumental in redefining the examination process for drinking water operators and developing a national backflow prevention tester examination.  As a function of his consulting business, he provides technical support and consultation to the water works industry and others with respect to cross-connection control and on-line training. He holds a BS degree from the University of Massachusetts.