Think Backflow Doesn't Happen? Just Look at Corpus Christi.

By now you have surely heard about the backflow event in Corpus Christi in December 2016. It was one of the rare times that backflow prevention and cross connection control made the news. On December 14th, citizens were told not to use their domestic water. For about 4 days, residents were unable to use tap water even if they boiled it or otherwise tried to treat it. As of December 18th, all three zones of the city could use their water once again, but it wasn't until December 27th that the EPA and TCEQ stopped receiving complaints about undrinkable water and water related illness. This may seem outrageous and unprecedented. However, this is actually the fourth time in recent years that Corpus Christi has had a backflow incident. Here is a breakdown of each event.

July 2015

The first two incidents took place in 2015. First, starting on July 23rd, the city issued a water boil notice after they found E. coli contamination. It took two days to flush the system entirely of the contamination and at 8 pm on July 25th, the boil advisory was lifted. The bacteria was found through monthly random water testing on July 22nd, and the city tested samples from the contaminated area again and confirmed the "elevated levels" of bacteria. The city manager cited high temperatures and low use as possible contributors but that a cross connection was the likeliest problem. This was the city's first backflow event since 2007. Officials did not give much if any information on how they planned to keep this from happening again.

September 2015

The next event took place in September 2015. In early September, low levels of chlorine were found in certain areas of the city. It was revealed to the city council that some water valves were closed, which led to stagnant water and caused the low chlorine levels. The city was supposed to keep track of all open or closed valves. However, the system for doing so was not being used properly and so they were not aware of these closed valves and it could very easily cause a problem again. The low chlorine levels meant that harmful bacteria could grow to unsafe levels and in order to keep citizens from getting sick, the city again issued a water boil advisory. This time, they tried to keep this advisory localized and only three areas of the city were affected starting on September 5th. Two more areas were added, and one was expanded over the next week. The water boil advisory was in effect until September 16th. After this much longer event, officials starting working on a plan to keep the water moving and clean. 

May 2016

The third incident happened eight months later when the city once again noted low chlorine levels in multiple areas of the city. The first positive sample was found on May 6th, and a water boil advisory was issued on May 12th after the TCEQ required the city to do so. The boil advisory affected all Corpus Christi water customers and this time it lasted until May 25th at 5pm. The city manager actually resigned midway through the event and it attracted the attention of environmental activist Erin Brockovich. The citizens were angry at having to deal with three water boil advisories within a year and called for the mayor to resign as well. Officials stated construction and old pipes as the biggest contributors to the problem. However, the city manager's office maintained the attitude that there was no way to guarantee that these problems would go away. Finally, they were moved to action and created a more detailed "source-to-tap" plan to keep the drinking water safe. Most of their planned updates were completed in November 2016.

December 2016

Unfortunately, the worst was yet to come. On December 1st, the city started getting calls about dirty and smelly water from Ergon Asphalt and Emulsions, an asphalt plant. There were also calls on December 7th and 12th. After the fourth complaint that month, the site was investigated. Unable to find the source of the problems, the city called in the TCEQ. On the 14th, the entire was city was told "do not use the water." This was much more severe than a boil advisory. Residents couldn't take showers or wash their clothes and they could not drink the water even if they tried to purify it. Over the next four days, the city, along with the help of TCEQ and the EPA, was able to find the source, fix it, and flush the system. By 11 am on December 18th, the whole city could once again use the water.

Officials found that the backflow preventer at that asphalt and emulsions plant was not working properly. It had failed and let a chemical called Indulin AA-86 as well as Hydrochloric Acid into the water supply. According to Hydroviv, a water filter manufacturer, this likely meant that the Indulin AA-86 which had backflowed into the water supply was already mixed to form an emulsion and it was likely that an entire tank had backflowed. An entire 8,000 gallon tank.

If you're unsure of what backflow is and how often it can occur, watch this video for a breakdown.

Follow Regulations, Get Safe Drinking Water

The backflow event in December could have been so easily avoided. The backflow device had not been tested annually as is required in most areas. In the past, local plumbers were given a list of commercial and industrial water users that had not had their backflow preventer tested yet for the year. That practice was discontinued for fear of terrorists getting this information. It's led to many backflow devices going untested. These things happen when cross connection control programs are not given the support they deserve. Clean drinking water should be a high priority for all municipalities, but it's so often swept under the rug away from the public eye and from funding. That is why in 2015 there were 1,550 boil-water advisories in Texas alone. Water districts and their staff need the support of their customers as well as the local government in order to do their job and keep our drinking water safe. Water districts must stay up to date on regulations and enforce them. That includes annual testing of backflow preventers and working closely with local plumbers and engineers. Engineers likewise need to stay informed so they can design water systems including backflow preventers according to those regulations. Instead of keeping with the status quo, engineers should make sure they design systems for long term safe drinking water.