Monday, March 28, 2016

Do You Have Lead in Your Drinking Water?

You might have lead in your drinking water, but lead does not exist in in most groundwater, rivers and lakes- the source water for most municipal and private water supplies. In addition, water treatment plants as required by the Safe Drinking Water Act test for lead before the water leaves the plant. It is exceedingly rare to have lead in groundwater or rivers as a result of pesticides that were used decades ago or industrial activity that contaminated soil and groundwater. However, it has been estimated that 20% of urban households and an unknown number of rural household have lead in their drinking water above the 15 parts per million that is the federal Safe Drinking Water standard. So where is the lead coming from?

The lead in drinking water is predominately coming from the pipes. Lead in drinking water is most likely to occur in homes built before the mid-1950s when the water service lines delivering water from the water main in the street into each home were commonly made of lead. Lead was also used to solder copper pipes together before 1988. Also until very recently (after implementation of the 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. So even a home like mine built with PVC piping in the 2000’s has some lead in most of the faucets.

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 that 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 (low in dissolved solids like calcium and magnesium) tends to be more corrosive than hard water (with high concentrations of calcium and magnesium), 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.

In addition, water that sits for several hours or overnight in a pipe or brass fixture can leach lead from the brass faucet interior which may produce high lead levels in the first draw of drinking water. Though faucets purchased after 1997 contain less lead than previously used, they still can leach some lead -as evidenced by the detectible but extremely low “first draw” lead levels I find each year in my own plumbing. The most recent legislation, the 2011 Reduction of Lead in Drinking Water Act also called “Get the Lead Out,” mandates that after January 4, 2014, all faucets sold in the United States will contain no more than a weighted average of 0.25% lead in relation to wetted surface and can be labeled “lead free.”.

Lead can cause damage to the brain and kidneys, and can interfere with the production of red blood cells that carry oxygen to all parts of your body. The greatest risk of lead exposure is to infants, young children, and pregnant women. Scientists have linked the effects of lead on the brain with lowered IQ in children. If your home was built before 1990 the only way to know if you have lead in your drinking water is to test.

The U. S. EPA limit for lead in drinking water is 15 parts per billion (ppb), but only requires action if limited sample monitoring for lead has not exceeded the 15 ppb action level in more than 10% of the homes tested. Cities are only required to test a very small number of homes monthly and the condition and age of the plumbing in the home really determines if lead levels will be elevated. You need to test your own home.

The true prevalence of lead in public water supplies at the tap is difficult to know because it depends on how corrosive the source water is, whether lead distribution lines are used, and whether a particular building contains leaded plumbing materials. Lead may also originate from the corrosion of brass fittings on certain types of submersible pumps used in private groundwater wells through the mid 1990's.

If you have elevated levels of lead in your home’s water you need to take action to reduce any potential exposure.
  • Replace the entire lead water service pipe. Typically water service lines a partially owned by the municipality and the portion on private property is owned by the homeowner. In Fairfax County homeowners are responsible for the entire service line from the water main. Replacing only a portion of the service line may actually make the problem worse. 
  • Replace the leaded components in the plumbing system with newer, non-leaded components. This usually requires replacing copper pipes and lead solder with plastic PVC or PEX pipes. 
  • Install an end-of-tap water filter. Look for filters certified by the National Sanitation Foundation for lead removal and reduction. Install this filter on the tap you use most often for cooking or for water to drink. Be aware that these small units are limited in the amount of time that the filter is effective in removing lead. Reverse osmosis units and activated alumina filters are very effective in removing lead once it is in the water. These units typically are attached to the kitchen tap and treat only the water from that tap.

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