By Hans Peterson, Saskatchewan Research Council, Saskatoon
A recent survey of municipalities by Sask Water has revealed that a majority of respondents are concerned about the safety of their drinking water. The same survey found that less than half of concerned respondents are willing to pay to improve their own water quality. The survey included all rural and urban municipalities in Saskatchewan.Whether we spend any more money on improving water quality, our society as a whole is already paying a steep price for not providing safe water to all its members. Rough estimates of the cost to Saskatchewan caused by the consumption of untreated or poorly treated surface water indicate there are between 700 to 1,000 reported cases of Giardia lamblia (Beaver Fever) per year. Actual cases could be as many as five times higher. The cost to Saskatchewan is likely in the order of $1 million to $5 million per year for Giardia alone.
We know much less about some other microbial illnesses, such as those caused by Cryptosporidium. In one case in the United States, it is believed that more than 100,000 people were exposed to Cryptosporidium when filters in a water treatment plant were not operated effectively. Effects generated by these parasites include chronic diarrhea.
The major surface water issues related to microbial illnesses and the disinfection of water are summarized in a statement by the U.S. Environmental Protection Agency (1993, Preventing Waterborne Disease). The statement reads: "Only good quality water can be disinfected." If we try to chemically disinfect water that is of poor quality, the chances are high that the water is still not microbially safe because microbes are protected by particles (see figure 1).
Communities or individual farmers that have poor quality water will notice that a great deal of chlorine is required to get a chlorine residual. In the example shown in Figure 2, dugout water was increasingly treated and chlorine was then added to get a certain residual. Ten times as much chlorine was needed for the untreated dugout water compared with the water after biofiltration and slow sand filtration.
Cleaning up the water before disinfection reduces the amount of disinfectant required, making it easier to disinfect the water so it is safe to drink. Reducing the disinfectant dose will also lead to lower levels of undesirable chlorinated organic chemicals produced during the disinfection process.
The Agriculture Green Plan Surface Water Quality Initiative (see article in this edition) is aimed at addressing the problems of surface water used for consumption. It is designed to develop cost-effective methods to reach the goal of safe and palatable drinking water. At the end of the four-year initiative, questions such as "Is this water safe?" should have clear answers. If protection of the catchment area for the dugout is implemented and combined with dugout management and effective in-house treatment the ansewr should be a resounding "You bet it is."
