Friday, May 17, 2013

Using Backflow Testing To Prevent Contamination

By Antoinette Quinn


Contaminated water flowing into drinkable is a real challenge for both public utility companies and homeowners. Unsafe water can sometimes be pushed back into the potable water source by pressure or even sucked back into it by negative pressure. These problems can arise during fighting fires, routine pipe maintenance, or even by a homeowner who has improperly installed pipes. One way to make sure the water is safe is to conduct backflow testing.

Backflow is quite simply when the water flows back to the source. This is a major problem if it runs back into drinking water because it can be contaminated. This is usually caused by either back pressure or back siphonage. Public utility companies have a legal duty to make sure that water is safe and untainted so they generally have some sort of prevention program in place.

Back pressure is a common cause of contamination. Pressure in the line pushes the pollution back into the clean water supply. This can happen when the pressure is off balance and is too low at the filtered end. Sometimes this happens when pipes break, when boiler temperatures are raised, or even when too much water is pumped.

Back siphonage is when the dirty water has a negative pressure and is sucked back. Usually the root of this problem is a stoppage of some sort; a broken water main or even significant use by fire fighters can cause this. Either way the polluted water becomes unsafe to drink and can lead to illness.

The most common method of preventing this problem is to implement a cross connection program. This method is often used by public water suppliers, such as cities and counties. There are many different ways of creating a good cross connection such as air gaps, reduced pressure assemblies, double check valves, and pressure and atmospheric vacuum breakers. Some home owners will also need to make sure they have a good program in place, especially if they live outside city limits.

The easiest method is the air gap. When installed and maintained the air gap is a relatively low maintenance system and can prevent water pollution. However, this is not recommended for major suppliers as the air gap is quite easily defeated. The air gap process is simply a way of separating the receiving and supply pipes so contamination cannot spread.

It is more common and for utility companies to use either reduced pressure or double check valves because they are effective in nearly every situation. However, they are mechanical devices and are subject to breakdowns and parts can erode over time so testing must be conducted on a regular basis. Testing for backflow can only be conducted by a certified tester. Backflow testing can also be useful for homeowners who want to make sure their supply is safe.

Backflow testing of cross connection programs is an essential part of your water supply program. While you can look at an air gap to tell if it is still working properly you cannot do this with mechanical systems. Certified testers should be used to test all of the moving parts to make sure your backflow prevention system is functioning properly.




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