Household Water Safety: Protecting the Family

Fun Fact: Americans drink more than one billion glasses of tap water daily.

A community water delivery system makes it so convenient: walk to the nearest sink, open the faucet and get healthy drinking water. We rarely even think about whether it's safe. Your community water supplier thinks about it though. Every day.

By law, water suppliers must ensure the health quality of water they deliver. But once it flows into the customer's plumbing system, the supplier no longer controls it. If a customer's plumbing system is cross-connected to sources of chemicals, pathogens, bacteria, or other contaminants, the supplier's system and all consumers are at risk. Reverse flow of water through those cross connections represents a danger to the public health. Potentially dangerous cross-connections even exist in our own homes.

Backflow is the reversal of the normal flow of water. The normal flow is from the supplier to the end user.
Backflow can be caused either by suction (called backsiphonage) or by backpressure.
A cross-connection is any connection between the potable (drinkable) water supply and any source of contamination or pollution.

Backflow becomes a problem when water in a plumbing system is mixed with any other substance, and then is pumped or sucked back into the potable water pipes. In the United States, there are many documented cases of illness and even some death resulting from contaminated water. Fortunately, the Uniform Plumbing Code and water suppliers across America are focused on the danger of these cross connections. Cases of water-borne illness are becoming less frequent and less severe. Backflow prevention helps improve the public health.

What about the customer's home plumbing system? Could backflow occur within our home and contaminate our own water? YES. The University of Southern California found direct cross connections to health hazards in 9.6% of surveyed household plumbing systems. This study also found that another 86.1% of household plumbing systems were indirectly cross-connected to health hazards (USC, 2002). These figures should focus our attention on the health of our families. Household cross-connections, like all others, can be eliminated or protected. Following are some of the most common cross-connections and some ideas to help you protect your family.

                                                                                                                              The most common direct cross-connection to a health hazard found by USC is an improperly set up toilet. Ensure all toilet fill valves are air-gapped to prevent backsiphonage of tank water, chemicals, and bacteria into the household plumbing system. Ensure the Critical Level mark is 1" above the top of the overflow pipe and the refill tube discharge is above the overflow pipe.                                

Irrigation Sprinkler Systems should have either: one properly installed atmospheric vacuum breaker (AVB) per zone; or a pressure vacuum breaker (PVB) upstream of the whole irrigation system. Proper AVB installation is: vertical orientation at least 6" above the highest sprinkler head in the zone, and not pressurized for more than 12 hours in any 24 hour period. Proper PVB installation is: vertical orientation at least 12" above the height of the highest sprinkler head in the system. Swimming pool fill lines should be protected with a PVB or a Reduced Pressure Principle backflow preventer.


A hose bibb vacuum breaker is a small, inexpensive device designed to prevent reverse flow of contaminants through a garden hose. Family health can be threatened during an incident such as what happened in New Jersey when a water main break caused the poison chlordane to be sucked out of an exterminator's barrel, through a hose and into the drinking water pipes of the home.

Garden hoses are commonly (but inappropriately) left unattended and submerged while filling or flushing pools, ponds, tanks, etc.  Each hose bibb should have a vacuum breaker permanently attached.

Laundry sinks/tubs should not have hoses connected to the faucet.  The outlet of the faucet should be at least one inch above the top (overflow) of the sink.  This creates an air gap to prevent pollutants or contaminants from the sink being backsiphoned into the household plumbing system.

Untreated secondary water sources such as wells must always be kept separate from the drinking water system. If there is a connection, the household system must be protected from the secondary source by a reduced pressure principle backflow preventer. The assembly must be tested and maintained regularly. The water district will also require an RPP at the meter.

                                                                                              If you lack training or skill in any of this work, seek a licensed, insured trade contractor. Our kids, pets and neighbors will thank us for doing our part to ensure safe water.