Thursday, May 4, 2017

Lead in Drinking Water

Lead in drinking water is a national problem. Flint Michigan was not an aberration nor was it the worst incidence of lead in drinking water supplies, but rather some combination of determined population, blatant misrepresentation by public officials, the public sentiment combined with the good luck of engaging Professor Marc Edwards of our own Virginia Tech allowed Flint to become the poster child for lead in drinking water that Washington DC failed to become ten years earlier. In a recent examination of data, Reuters found 3,000 communities that had recently recorded lead levels at least double those in Flint during the peak of that city’s contamination crisis.

Elevated lead blood levels in children can come from more than water- lead based paint in older homes is a particularly notable source, we have made great progress on reducing exposure to lead based paint. The lead in drinking water is predominately coming from the pipes. Lead does not exist in in most groundwater, rivers and lakes- the source water for most municipal and private water supplies. Instead, lead in drinking water is picked up from the pipes on its journey into a home. In older homes the water service lines delivering water from the water main in the street into each home were commonly made of lead. This practice began to fade by the 1950’s but was legal until 1988. Lead was also used to solder copper pipes together before 1988 (when the 1986 ban on lead in paint and solder went into effect). Also until very recently (2011 Reduction of Lead in Drinking Water Act) almost all drinking water fixtures were made from brass containing up to 8% lead, even if they carry a plated veneer of chrome, nickel or brushed aluminum and were sold as "lead-free." So even homes built with PVC piping in the 2000’s may have some lead in most of the faucets.

The presence of lead in pipes and fixtures becomes a bigger problem the older the pipes and fixture become. Over time older pipes and fixtures corrode or simply wear away and the lead and other corrosion material (like rust) is carried to the drinking water. Time and water do cause corrosion, but this can be aggravated by the pH of the water or other changes in water chemistry. The amount of lead corroded from metal plumbing generally increases as water corrosiveness, a factor of the water’s acidity and calcium carbonate content, increases. In general, acidic water that has a pH less than 7 and is low in calcium carbonate is more corrosive than water that has a pH higher than 7 and that is high in calcium carbonate. Soft water tends to be more corrosive than hard water, and warm water is more corrosive than cold water. The common practice of grounding electrical connections to water pipes also can increase lead corrosion in the pipes.

There are about 75 million homes across the country built before 1980, meaning they’re most likely to contain some lead plumbing, though homes built until recently can contain some lead containing plumbing fixtures. That's more than half of the country’s housing units, according to the Census Bureau. The heaviest concentrations are in New York, Rhode Island, Massachusetts, Connecticut and Pennsylvania. In addition, there are an estimated 7.3 million homes connected to their utility's water mains by individual lead service lines. These homes and buildings are mostly in older cities. These lead service lines are owned in part or whole by the property owner and should have been replaced decades ago.

You cannot taste or smell lead. The only way you can know if there is lead in your water is to test. The U.S. EPA determines that a system has exceeded the lead standard when more than 10% of samples taken show lead levels above 15 parts per billion. It's called an "action level" because, at that level, water systems are required to take some action to reduce contamination. The problem is very few samples are required to be taken each year a water system and there is no safe level of lead. 

 U.S.EPA rules require lead (and copper) to be measured inside a home usually at the kitchen sink. In small community water systems, five to 10 homes are sampled initially every six months. The frequency of sample collection is reduced to annually and subsequently to three years based upon consistently meeting the action limit. That is not nearly exhaustive testing and community systems and schools have limited staff and resources to address these issues. There are 2,724 listed public water supply systems that are required to test their water in Virginia alone. Many of them are parks and entertainment venues, schools and tiny community systems on well water. All have limited resources. A problem could go on for years or a decade before it was discovered. Test your home water. Some large community water systems like Fairfax Water will do the analysis for you. In other places you are on your own.

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