"safe" depends on what those TDS actually are. For example, you're allowed to have x ppm nitrate (it's actually about 44.5ppm nitrate), x ppm phosphate, x ppm this, x ppm that in drinking water.
If the levels in the municipal supply get too high - as I believe they can in Abbotsford due to agricultural contamination of the Abbotsford-Sumas aquifer, they'll pipe in water from some other source and mix it with the municipal supply to dilute the contaminants until they're below the legal limits, which means that over the course of the year the primary source of the water coming out of your taps is probably multiple locations that get blended at different ratios depending on conditions at the time.
Also, the Abbotsford-Sumas aquifer's water table is only a couple of meters below the surface, which makes it very, very shallow from an aquifer point of view, so it's highly susceptible to fluctuations due to surface leaching in response to weather. According to my friends in the hydrogeology department, that aquifer's recharge and flow direction is generally toward the south (meaning that the Canadian side of the aquifer usually has less contamination at the depth we drill our wells), so depending on when people are fertilizing the fields, and when it's raining, and how long it takes contaminants to reach deep enough to make it in to the pumps that bring it back up, I'm not surprised that there would be pretty wild fluctuations over the course of the year.
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11-26-2013, 04:42 PM
Hybrid Mode
