Safe drinking water for rural Canadians

In a recent CMAJ editorial, Steve Hrudey correctly stated that Canadian water quality is a rural versus urban issue.¹ Canadian cities have some of the best-quality sources of raw water in the world and the financial and technical resources to treat the water with processes that take hours and use sophisticated techniques. Most cities treat their water to standards even higher than those outlined in federal or provincial guidelines.

In contrast, raw water supplies in rural Canada are often small and of poor quality. The water drains mostly from farmland and may contain Escherichia coli and other bacteria, parasites, viruses and organic material that can be difficult even for city-based treatment plants to remove. Most rural communities treat their raw water supplies using only a few simple processes that take minutes.

This is the crux of the problem: rural water needs better treatment than urban water because it is of poor quality. Is it any wonder that most rural water treatment plants cannot meet current Canadian guidelines for drinking water quality? In many rural communities, drinking water is assessed using only a small subset of the guidelines and the response to boil-water advisories is often just to add more chlorine.

There are 2 ways to solve the problem with rural water supplies. The first solution is to pipe in water from regional treatment plants. This approach may make financial sense but there may be microbial issues, such as the growth of nontuberculous mycobacteria.² Unlike urban distribution systems, rural pipelines are typically very long and have a small diameter. The use of small-diameter pipelines results in long water residence times, higher surface area and loss of disinfection residuals. Attempts to increase the longevity of these residuals (e.g., by chloramination) are not effective when oxidation- resistant bacteria such as nontuberculous mycobacteria are involved. Many organizations and agencies that promote a pipeline approach have in the past labeled pipeline water as nonpotable even when fully treated water was being distributed. This permitted local authorities to circumvent any requirement for water quality testing to comply with drinking water guidelines. Few consumers receiving this water would bother to retreat it as they believed it must be of high quality because it was provided by government agencies.

A simpler and universal solution exists. Better water treatment systems are needed for rural water users.