The City of Ottawa supplies high quality drinking water to a population of 780,000
through the operation of two surface water treatment plants and a large distribution
system some of which dates back to 1874. Since the source water (Ottawa River) tends
to be aggressive owing to its low hardness and alkalinity, corrosion control has been
practiced for 75 years, primarily through pH adjustment. In recent years, the corrosion
control strategy has been reviewed and updated to provide better protection of the
distribution system.
In 2002, a localized area of the distribution system experienced elevated lead levels in
residential water samples that exceeded the drinking water standard for flowing lead
concentrations at the point of consumption (10.0 µg/L). The situation was resolved
through quick adjustment of the corrosion control strategy. Recent initiatives have been
undertaken to monitor corrosion in several pipe loop systems and determine optimum pH
conditions to minimize lead and iron dissolution.
In addition, a residential testing program has been carried out to determine typical lead
exposures due to piping and plumbing materials and to assess the impact of lead service
line replacement. The testing has evaluated lead arising from both transitory and
stagnation contributions to lead in the tap water. The sampling program makes use of
sampling methods described in Health Canada's proposed Guideline Corrosion
Control in Drinking Water Distribution Systems as well as random exposure testing to
assess typical exposure through domestic water use. Includes figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.8 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 65 |
| Published : | 06/01/2007 |
