Tales of a tester

By Steve De Vidi, DVD Backfl ow Inc.

Although it was not a true backflow incident, the event in Walkerton, Ontario was a big eye-opener for the general public, making them aware that the water that runs out of their faucets and is so easily taken for granted, may not always be safe for human consumption.

With the exception of an Air Gap, a backflow preventer is the best protection against cross connections we have. Other than the manufacturer’s approval, the most important and, more often than not, the ‘only test’ a backflow assembly receives is after it has been installed. Failure of a backflow preventer will most likely happen the first time water is run through it! This is due to the fact that the water lines may have not been thoroughly flushed. Filling a water system for the first time can cause some serious problems. Where it is possible, it is always wise to ensure that all new water services that are installed be flushed thoroughly before the balance of the distribution system is installed. This is an NFPA requirement for all new fire protection mains and should be inspected by the local authority having jurisdiction. It would certainly make life easier for the backflow assembly tester.

Thoroughly flushing the water main is good practice. However, through the construction phase, systems can be filled and drained several times, pushing grit, dirt, and often residue from pipe walls, further into the system, usually ending up lodged in the check valve seats of the backflow preventer. Pressure tests can also cause abnormal conditions within the system, causing damage to new backflow devices. Since backflow preventers are tested in the factory, the initial test is better done prior to the final plumbing or sprinkler inspection when all water systems have been thoroughly flushed, drained, filled again, and are ready to commence normal operation. If a backflow device is tested immediately after installation, the debris may end-up inside the device for a year until it is retested, or damage done to an abnormal condition could go undetected, both resulting in a backflow incident.

With repairs, retrofits, upgrading and flushing of water systems constantly going on in every purveyor’s jurisdiction, it is hard to determine just when a backflow device may fail due to dirt or damage. I am a strong advocate of annual testing as a safe method to ensure that backflow preventers continue to do the job they were intended to do. In some of the more progressive cities, towns and water districts of this province, annual testing is mandatory though active cross connection control programs. I annually test a small strip mall with five buildings. Spread throughout this complex, there are 30 testable backflow assemblies. One particular year, I had something unusual occur. In three of the five buildings, one or two of the assemblies failed their annual test. Upon opening the assembly for inspection, I found a rather thick, tar-like mud deposited around the check valves. At first, I was puzzled as to why only a few of the assemblies were affected, and why in only three of the five buildings. Then it struck me—the assemblies that had failed were installed on systems that were running continuously throughout the night. Those buildings that were not drawing water did not have any failures due to this mysterious tar like substance. As I pointed out earlier, you just never know when something alien may enter a water system.

One of the biggest problems in the industry is fraudulent testing. There has been concern raised about cross connections possibly contaminating our water supply. With all the in-depth detail of liability a tester is responsible for, and is informed of when he takes his cross connection control exam, it saddens me to come across reduced pressure backflow assemblies with seized diaphragms caused by intentional tampering. To find a double check valve assembly tagged as repaired last year, only to open it and find all parts just thrown in and closed, is criminal. I am sure most testers are doing their job properly, but it only takes one incident to destroy a successful program.

In areas that do not have, or endorse, a cross connection control program, and in some in the early stages of development, I have found some interesting things. In once instance, I found shavings of blue brute inside the check valves. This indicated that the initial test had just simply been filled out on the attached paper in a fraudulent fashion. There was absolutely no way that assembly would have passed the initial test. Depending on the operation and installation of a backflow device, water may flow more through the bottom or the top of each check valve at different times, making it easy to latch on to passing debris. Therefore, attempting to flow debris through a backflow device after it has failed is often unsuccessful. Only physically opening the device and wiping the check valve and seat clean will ensure the check valve will hold the appropriate pressure.

Finally, some thoughts on the content of some of the tester courses available. First, more emphasis should be put on the liability issues, not only with testers, but also owners and purveyors. Second, is in dealing with the various types of backflow preventers and assemblies that are out there. With new assemblies and devices appearing in the marketplace on a regular basis, it is sometimes difficult to keep up. Different problems and solutions come with different manufacturer’s products, and it is just a matter of trial and error before you can effectively repair all backflow devices. Like a new automobile driver, it takes hands-on experience to achieve understanding, knowledge and success in this ever-changing world of backflow testing, installation and repair.

Maintaining a good working relationship with my clients, it is very important. There are some helpful hints that may be of benefit to those of you who read this article, especially those who are just starting in this field. Use Air Gaps where possible. You may loose the cost of installing a testable assembly and a yearly fee for testing, but you will gain the respect of your client by having saved him some money, and that can be an advantage for future business. Always check with the local authority having jurisdiction where any questionable situations arise, particularly those areas with active CCC programs. The requirements on certain plumbing fixtures and equipment that require the installation of a backflow device may vary between areas, because of interpretation, bylaw content, and risk management issues.

The Good
DCVA installed above ground in a heated shed.

The Good

The Bad
RPBA installed without testing or maintenance for 12 years. Failed due to tampering with check valves caused cross connection.

The Bad

The Ugly
Someone did this to avoid testing or perhaps the assembly was not functional.

The Ugly

In regards to Premise Isolation, more often than not, two devices should be required. I annually test a hotel that has a 6” diameter DCVA as premise isolation. There is never a good time to test it, as the hotel is always using water. In consulting with the maintenance manager, we came to an agreement that a 2:30 to 3:00 p.m. time slot would be the best time to test. I have two of his assistants work the shutoff valves, while I perform the test. Fortunately, in three years, it has passed three times. The day it fails, will be very challenging indeed. I also test a medical facility with premise isolation. The first time I arrived on site, the owners had me come on a Saturday to replace all the rubber parts on this six inch RPBA. Neither one of us wanted to be there on the weekend. The following year after some budget alignment, a second RPBA was added for this same service line, making things much easier to deal with. It would have been more economical to have done this at the initial construction phase. Repair to an existing backflow assembly can take anywhere from 20-60 minutes. Premise isolation has become more popular in some cities recently, partly due to the events of September 11, 2001, with the realization of how important safe drinking water is to all of us.

Footnote: The Cross Connection Control Committee wishes to thank Mr. De Vidi for this fine article, and encourages others in the backflow industry who are interested in submitting ideas or articles to contact us through the BCWWA website.