Our Domestic Water System

The most serious risk of contaminants - bacteria, chemicals, physical material - entering domestic water systems like ours is a cross connection. This is any potential or actual pathway for non-potable water to enter our domestic lines. The most common cause is loss of pressure in our lines resulting in siphoning water from a garden hose, stock tank or spray tank. The pressure loss could be due to a power outage, a major leak, a system shut-down for repair, or an un-commanded shut down of the well-pump or booster pumps. All these causal events have occurred in the last year resulting in adverse coliform bacteria tests. An incident last year was the result of leaving an unattended running hose coiled in a stock tank to avoid freezing. There was a pressure loss due to a power outage and a slug of stock tank water was sucked into our mainline. We were lucky that no-one got sick, or worse. Next time could be catastrophic. If we have one more bad water sample we will be required to use full-time chlorination resulting in sharply higher water fees to owners. We would have to test chlorine levels daily.

It is therefore imperative that owners take steps to eliminate cross connections and prevent a public health threat from ever recurring in Vista Vue. The first step is to identify potential cross connections on your property. To this end the Board of Trustees will be sending out a follow-up to the cross-connection survey conducted in 2008. The survey is a self-assessment of cross-connection risks.

The remedies for cross-connections are quite simple: Always maintain an air gap between the inlet water source and the rim of the tank equal to at least double the diameter of the inlet pipe (1-1/2" for a 3/4" hose). Automatic stock watering valves that clamp to the rim of the tank do not have an approved air gap, but they can be adapted to provide one. Where it is difficult or impossible to provide an adequate air gap to prevent a cross connection, an approved back-flow assembly - two check valves separated by an air chamber - must be installed and inspected once a year by our contracted system manager. A back-flow assembly is required to provide isolation of high hazards, including agricultural operations. Only State-approved back-flow assemblies may be used; they cost about $80 plus any installation expense.

It is recommended practice to install a vacuum-breaker on all outdoor hose bibs before the hose. These are simple inexpensive devices that prevent back-flow resulting from system pressure loss. While not a State-approved back-flow prevention assembly, vacuum breakers do provide an added degree of protection against cross connection.