Safe drinking water is critical for humanity. The local water department has the primary responsibility of keeping the public water system free of any types of contaminants. Consumers – whether commercial businesses, property owners or homeowners – also have some responsibility to assure that contaminated water doesn’t flow back to the drinking water supply. A backflow prevention device is used to protect potable water supplies from contamination or pollution.

Your water is typically distributed in one direction: from the water supplier to the consumer. It is possible, and not all that uncommon, for this water flow direction to be changed by various hydraulic conditions causing water flowing from the consumer to the water supplier. This is process is called Backflow. This water can be from non-used systems containing stagnant water or irrigation systems which may be contaminated with fertilizers, pesticides or other objectionable materials.Think of a simple garden hose with a fertilizer / pesticide tank sprayer attached to it. The hose and tank lay out in the summer sun, heating the water inside the hose and tank. Through thermal expansion the pressure in the hose increases higher than the normal city water supply. The contaminated hose water is then pushed back into the water source, your homes plumbing and the public water supply. This is why it is important to always keep the spigot valve closed when not in use.

Testing of Backflow prevention devices are required to be tested annually to ensure that they are functioning properly. Mechanical backflow preventers have internal seals, springs, and moving parts that are subject to fouling, wear, or fatigue. Also, mechanical backflow preventers and air gaps can be bypassed.  A visual check of air gaps is sufficient, but mechanical backflow preventers have to be tested with properly calibrated gauge equipment.