This really isn’t news around London, unless you haven’t been paying attention, but there are elevated lead levels in the city’s drinking water, especially in the older parts of the city, where commonly, before the 1950’s when lead was banned, lead pipes were used to, at least, run water to houses from the main line.
Anyway, as an airport book, I picked up Flushed by Hodding Carter – a fan of plumbing – published in 2006.
… The EPA has has something called the lead and copper rule that requires water utilities to monitor the amount of heavy metals in their customers’ homes. Aggressive water, as the utilities call it, can exacerbate the leaching of metals into households. Water that is acidic or has too much chlorine is aggressive and breaks down the metal. If you have lead solder in your pipes, as most older homes do, it can deliver that lead directly to your body. It also breaks down copper, ingesting too much of which can lead to kidney and liver damage. …
and from the Free Press article; Lead woes go back 12 years, from Thursday, June 7, 2007:
For 12 years residents have been drinking water far more acidic than what would be tolerated by a U.S. utility whose customers have lead pipes, says a chemist with the U.S. Environment Protection Agency (EPA). Anywhere in the U.S. with lead pipes, utilities try to keep the pH above 9 and regulators intervene if it drops below 8.5…
While a number of things cause lead to leach from pipes, solder and fixtures, the biggest culprit is water that’s overly acidic, experts say. But since 1995 in London, which has 13,000 homes with lead pipes, pH has rarely gone above 7.5 and has dropped as low as 6.5 … A one-point drop in pH can cause lead in water to surge sixfold … There aren’t requirements in Ontario about pH in drinking water, but there’s been a standard practice to keep the water pH between 6.5 and 8.5.
A pH 7 is neutral. A pH less than 7 is acidic.
A half-point difference doesn’t seem like much, but the scale is logarithmic.
Anyway, I hadn’t heard the phrase “Aggressive water” ever used before. Seems like many people know about the problem. It seems like ccommon knowledge in the industry. I wonder why the folks in charge of the problem in our town haven’t done anything about it for all these years?
I believe London pipes it’s water from Lake Huron, directly. Where is it treated before it reaches our faucets?
This page at The Ontario Ministry of the Environment shows a chart of pH and lead levels.
This suggests the water is coming in relatively lead free – less than .2 micrograms per litre – and with a good pH balance – above 8 – from Lake Huron, but by the time it hits our homes:
1. Emery St East between Cathcart St and Wortley Rd. Pre-flush: 10.4. Post-flush: 4.8.
2. Windsor Ave between Ridout St and Belgrave Ave: Pre-flush: 9.7. Post-flush: 5.5.
3. Mayfair Drive: Pre-flush: 3.5. Post-flush: 0.4.
4. Hyman St between Wellington and Waterloo streets: Pre-flush: 42.0. Post-flush: 10.6.
5. Adelaide St N between Queens and Dufferin avenues. First post-flush: 9.6: second post-flush: 7.4.
6. Queens Ave between Quebec and Ontario: Pre-flush: 15.2. Post-flush: 9.2.
Many homes meet the standard, but not by much – 17 % had levels between 5 and 10 micrograms, well above the level in the city’s distribution lines, which are below 1 microgram. Mayfair Drive, is in the city’s north end – closer to Arva. Hyman St is central city core; Adelaide, Old East; Emery and Windsor, Old South.
There remain elevated levels in communities throughout South Western Ontario, Hamilton, Sarnia, Queens Park in Toronto, and schools in London which are not in known hotspots. So it seems the lead values shoot up somewhere between the Arva distribution point and the faucet – made worse by the acid, Agressive water.
Update: Thursday, August 23, 2007