Drinking water may seem abundant, but it is increasingly in high demand and short supply. That’s why the plumbing industry has, over the last century, developed devices to prevent backflow and protect drinkable water.

Backflow basics
Backflow and cross contamination are the most common risks to our water supply.  Backflow prevention first drew attention in the late 1800s when a textile mill caught fire and river water was used to put it out. Contamination of the water supply ensued, which raised awareness of the need to protect our water from backflow.

Contamination occurs through backflow when there’s a reversal of water flow.  Water distribution systems are designed so that water flows in one direction – from the water supply to the consumer. Normally, potable water is delivered from the supply when pressure upstream moves it through the fixture and out the spout. If pressure downstream increases or if the system pressure upstream decreases (known as backsiphonage), non-potable water can enter the drinking water supply and contaminate it.

As a result of the aforementioned textile-mill incident, external check valves were introduced to protect the water supply. Initially a single check valve was installed alongside the discharge outlet and used to prevent backflow. However, these proved unreliable, and so a device with two checks was developed in the early 1900s. But it became apparent that in many cases these external valves were not being installed. Therefore, it became essential to develop an alternative, reliable means of providing backflow protection.

What’s on the inside counts
In 1996, the American Society of Mechanical Engineers (ASME) introduced the ASME A112.18.3 standard for backflow-prevention devices. This standard applies to plumbing fixture fittings with outlets not protected by an air gap, including fittings with hose connected outlets, fittings with pull-out spouts, hand-held showers, shampoo fittings and deck-mounted fittings. “New concept” devices, such as internal check valves, were recognized as an alternate to the external valves.

Internal checks allow manufacturers an opportunity to add backflow-prevention devices to products like hand showers and kitchen pull-out spout wands without being prohibitively costly and without compromising the design that consumers want.

You can locate these devices in the wand of the fixture fitting. They are designed to remain closed when the fixture is turned off and there is no water flow. When water flows, the pressure of the water pushes the valve open and allowa water through. If the pressure downstream of the valve increases, or if the system pressure upstream of the valve decreases and causes the flow of water to reverse, a spring-loaded plunger closes to prevent non-potable water from passing back through the valve and into the water supply.  Delta Faucet Company now installs two of these devices, manufactured by NEOPERL, in every hand shower and every pull-out and pull-down faucet.

The A112.18.3 standard also introduced a vigorous testing requirement for internal checks. Not only are these devices tested individually, but they must also be tested after they are installed in the fixture to ensure backflow protection truly exists. Additionally, the standard requires two separate backflow-prevention devices (check valves, vacuum breakers, vents to air or automatic diverters). At least one device shall be a check valve, called the primary check, and contaminants shall not be allowed to enter beyond this first barrier.

Testing of these devices has shown that they outperform devices that have traditionally been accepted in the plumbing system. Testing has also proven they are capable of standing up to the toughest standards in the industry.

What it all boils down to
By offering internal check valves, manufacturers are not only ensuring a more convenient installation process for the plumber and a more aesthetically pleasing sink or tub for the consumer, they are also accepting the role of leadership in the industry by promoting advanced products and the protection of public health.

More importantly, as the liaison between the manufacturer and the consumer, plumbers play a vital role. They must be leaders by selecting devices with internal check valves. By doing so, plumbers simplify the installation process while offering customers the best products on the market — and peace of mind.

 

Sally Remedios is Manager of Product Compliance, Delta Faucet Company