Thank you.
My name is Graham Gagnon. I am a professor at Dalhousie University. I'm the director of the Centre for Water Resources Studies and I'm also the NSERC/Halifax Water industrial research chair in water quality and treatment at Dalhousie.
With me today is Mr. Ben Trueman, a Ph.D. student from our lab. Ben has worked with me for the past five years on many lead projects, working directly with Halifax Water and other utilities in our region and across Canada.
Our research team has been looking at corrosion since 1998, when I started at Dalhousie. In particular, we have been addressing lead in drinking water since about 2008, when we first started looking at lead solder in copper pipes. Over these years it has been clear to us how complex the problem is with lead in drinking water.
In particular, in 2011 our research group at Dalhousie started an important study that investigated lead service line replacement, in collaboration with Halifax Water. In the first phase of the work, Halifax Water asked whether we can provide safe water through partial lead service line replacement.
As was touched on, a partial lead service line replacement refers to the fact that in most areas, the water utility is responsible for water infrastructure from the water main to some area on the property line. The homeowner is therefore responsible for the remaining part of the service line.
After four years of data collection, we published two papers. One paper was awarded the best paper by the Journal – American Water Works Association. Another was published last year in Environmental Science & Technology. This four-year study revealed that a partial lead service line replacement was an inadequate solution. Indeed, for many homes, the situation actually worsened following a partial lead service line replacement.
In contrast, our data showed that a full lead service line replacement was the best way to ensure the household would see lower lead levels at the tap and that partial lead service replacements were not recommended. Because of this important research, Halifax Water does not conduct partial lead service line replacements anymore.
A colleague of mine, Dr. Michèle Prévost, published similar work in 2017. In studying lead service line replacements in Montreal, Dr. Prévost's team found that the lowest levels of lead were found when a full service line replacement was conducted. These findings are consistent with our work and with recommendations from the United States National Drinking Water Advisory Council, or NDWAC, to reduce lead in the home.
In addition to studying lead service line replacements, our team has studied corrosion control. Corrosion control is a process whereby water utilities can chemically alter their water to minimize lead release. Even after lead service lines have been replaced, there is still a need to have corrosion control, as lead exists in solder, brass, drinking water fountains, and many household and commercial fixtures. Thus, full lead service line replacement removes the largest lead source, but corrosion control is still necessary for managing risks from these other sources.
Our research with Halifax Water has shown that orthophosphates are highly effective at managing lead. After two years of data collection, we determined that an increase of phosphate from 0.5 milligrams per litre to 1 milligram per litre reduced the burden of lead at the tap by more than 30%. Of course, there are other possible strategies that utilities can address for corrosion control, but what is important to recognize is that a utility might have to wait 12 to 18 months for these changes to reveal their effectiveness.
I'm presently working with the City of Regina to further minimize lead at the tap, even though Regina has very few lead service line occurrences. This work is just getting started, and it's becoming clear to us and to the City of Regina how complex the situation will be for them.
Our team has also investigated lead occurrence in first nation communities in Atlantic Canada. Although compliance on flushed samples is greater than 90%, we have found that non-compliant lead samples exist across 85% of Atlantic Canadian first nation communities. We have also published similar work on lead occurrences we found in communities in Nunavut. In other words, lead is ubiquitous in first nation communities as well.
It is recognized by utilities and first nation communities that minimizing lead is important for public health. Health Canada has now proposed a lower maximum acceptable concentration for lead, as described by my colleagues. This guideline is combined with a sampling strategy that effectively will change the paradigm for monitoring lead across Canada.
While I support the intent of lowering lead levels at the tap, after years of studying this issue, I can say that a very sufficient and long time will be required for utilities to get to an answer.