Originally this piece was going to be about the tap water issues in Flint, Michigan. It turns out the subject is a political hot potato with plenty of blame to be spread around. This is not the place to have that discussion. Curiosity got the best of me because there was lead in the water. Where did the lead come from? This is where we will depart from the problems in Flint.
Lead (pb) is extremely harmful to our bodies. Lead contamination leads to nerve and brain damage. In general, women are more susceptible than men to lead poisoning. Fetuses are more susceptible to lead poisoning than their mothers, fetuses will actually protect the mothers from lead poisoning. Lead causes infertility and spontaneous abortion. Lead is just something that is bad in our bodies.
So where is the lead coming from? From our lakes and rivers, lead is coming from our streets, pipes and soils. This is a very insignificant amount and is in general not the cause of lead poisoning. Drinking water standards in the United States allow for zero amount of lead in drinking water leaving the treatment plants. So if the sources of tap water for cities are rivers, lakes or ground water and it is treated before it leaves the plant, the lead pollutant is getting into the water between the water plant and our faucets. So that means our plumbing is the culprit.
Lead service lines are the major source of the lead pollutant in our drinking water. Fortunately lead lines were phased out in the 70’s and 80’s. Lead pipes were installed for use in Chicago as late as 1986. The problem is when pipes come in contact with water and oxygen, a layer of lead oxide forms on the inside surface of the pipe. This layer forms to protect the pipe from further corrosion. Over time water flowing through the lead pipe dissolves the lead and then ends up in out tap water.
Seems like a pretty simple and easy fix. Get rid of all the lead piping! It’s not that simple. There’s a thing called economics. It would be pretty tough to explain to a neighborhood that their taxes are going up again for a second straight year because last year’s new water lines need to be replaced with new copper water lines this year, and oh by the way you may have been poisoned.
Enter the 1991 Lead and Copper Rule, a regulation designed to protect Americans from the nation’s aging lead service lines. The regulation required utilities to test water from local homes for lead. If 10% of the samples exceeded 15 parts per billion, the utility was ordered to reduce the lead by chemical corrosion means. If that failed, water utilities had to replace 7% of their lines each year or until follow-up samples showed a reduction in lead levels. Seems like a reasonable fix, service lines are replaced or lead levels meet standards. Problem solved.
Problem solved? Not so fast. Chemists, these guys were not, who wrote the Lead and Copper Rule. When the new copper lines are connected to old lead lines using brass fittings a galvanic corrosion is initiated and that can greatly increase the amount of lead entering into the water. Lab experiments have shown copper lead pipe connections can release up to five times more than just the lead pipe alone. When replacing the lead lines the utilities can’t replace the home owner’s line unless they give the go ahead and pay for the new line going to the house. Well, who would not want a new line to the house and eliminate the potential for lead poisoning. Apparently 90% of American households said they were just fine with the old lead pipes. So maybe it really was not explained very well and also again economics were in play. Replacing the homeowner’s portion of pipe, from property line to house, is expensive. Cost can run from $2500 to $7000.00 or more depending on circumstances. That is a major chunk of change for most home owners. So it is safe to assume that there are a lot of lead-copper connections in older neighborhoods throughout the country.
It gets better yet. There are two ways of chlorinating water to disinfect it. Utilities either use free chlorine or chloramines. Chlorine forms higher concentrations of disinfectant byproducts that are not wanted in the drinking water. The switch to chloramines then reduces the disinfectant byproducts. This is good right. It would seem there would be less pollutants in the water, however again chemistry comes into play. Lead has different oxidation states. Without going into a lot of chemistry when utilities use the free chlorine which is a strong oxidant the lead pipes are fairly stable, upon switching to chloramines not as strong an oxidant, the lead goes to a different oxidation state and become soluble. So pipe scale that has been built up over the years in now release into water stream.
Chemistry, Chemistry, Chemistry. The water source of the utilities also plays an important role, dissolution rates of lead are a function of pH. A lower pH level will be more corrosive to the pipes. The pH varies from source to source. In the case of Flint, Michigan, the Flint River has a lower pH than the treated water from Detroit. If the Flint utilities did not increase the pH to that of the Detroit supplied water an increase of corrosion in the pipes would have happened. Also if Flint utilities used a different disinfectant than the Detroit utilities problems could have happened too.
In the end, there is more to our drinking water supply than meets the eye. It is like anything else we purchase for our homes, a manufactured product.