From the American Water Works Association (AWWA):

The United States is home to one of the safest drinking water systems in the world. Nonetheless, the Centers for Disease Control and Prevention reports as many as 32 million gastrointestinal illness cases every year due to contaminated public drinking water.

• These cases often result when water systems are not adequately equipped to prevent instances of backflow. Backflow is a hydraulic phenomenon in which contaminated water can reverse flow into piping that contains potable drinking water. Backflow preventers are mechanical valve assemblies that prevent reverse flow in a water system and ensure public drinking water safety in city water mains, commercial buildings, and at the point of use. Despite the inherent risks, more than 60% of public water systems are designed without proper backflow preventers.
• Purveyors are keen to follow the strict Statement of Policy on Public Water established by the American Water Works Association (AWWA), which reads: “The return of any water to the public water system after the water has been used for any purpose on the customer’s premises or within the customer’s piping system is unacceptable and opposed by the AWWA.” To that end, all commercial and industrial buildings must have backflow prevention on the supply side of the system to protect public drinking water from contamination. However, standards vary between state and local water jurisdictions regarding where and how backflow preventer assemblies are installed. If guidelines do exist, they are often outdated or are not reflective of current best practices. Without the availability of quick and accurate standard details, engineers defer to whatever was done in prior projects, unattuned to the potentially devastating consequences of installing backflow preventers inside a mechanical room or underground in a utility vault. From millions of dollars of destruction to injury and death, Murphy’s Law prevails. What can happen does happen, and all-too-often, the costs are incalculable. The Dire Need For Cross-Connection Control Programs While there is no easy fix for this problem, the AWWA believes that the collaborative efforts of municipalities, health officials, and building owners to develop and administer clear, comprehensive, upto-date specifications would vastly improve the cost, safety, and liability of designing and installing backflow preventer assemblies. “ AWWA encourages the partnering of utilities, property owners and other stakeholders to jointly develop measures to maintain water quality within premise plumbing systems. Operations should include at a minimum a cross-connection program, routine monitoring, and response training to prevent, detect, control, and resolve water quality issues.”
• Best practices in backflow prevention & protection what causes backflow to happen in the first place? The backflow of water occurs when a hydraulic event creates more or less pressure inside a water distribution system’s piping. Hydraulic events can trigger two types of backflows: 

 ASSE Backflow Certified Plumbers

•  BFPE International – 717-741-9980
•  Alexander’s Plumbing & Pumps – 717-642-5285
•  Baumgardner’s Mechanical, Inc. – 717-334-6398
•  Frantz Plumbing, LLC – 717-334-3424
•  Neubauer Plumbing & Heating, LLC – 717-334-0310
•  Trump Plumbing & Heating, LLC – 717-465-1412
•  B. Weaver/ Plumbing & Backflow Service – 717-743-8912

Backflow Prevention Assembly 

Test & Maintenance Form

 This form must be completed by an ASSE-Certified Tester

• NAWSC Test Form