Calculating Concentrations in Water
Concentrations of chemicals in water are typically measured in units of the mass of chemical (milligrams, mg or micrograms, ug) per volume of water (liter, L, l).
Concentrations in water can also be expressed as parts per million (ppm) or parts per billion (ppb). Parts per million and parts per billion may be converted from one to the other using this relationship: 1 part per million = 1,000 parts per billion.
For water, 1 ppm = approximately 1 mg/L (also written as mg/l) of contaminant in water, and 1 ppb = 1 ug/L (also written as ug/l). A measurement of 6 mg/L is the same as 6 ppm or 6,000 ppb, which is equal to 6,000 ug/L.
A way to visualize one part per billion (ppb) in water is to think of it as one drop in one billion drops of water or about one drop of water in a swimming pool. One part per million is about 1 cup of water in a swimming pool.
Occasionally, concentrations of chemicals in water may be written as grams per cubic meter (g/m3). This is the same as grams per 1,000 liters, which may be converted to milligrams per liter (mg/L). Therefore, 1 g/m3 = 1 mg/L = 1 ppm. Likewise, one milligram per cubic meter (mg/m3) is the same concentration in water as one microgram per liter (ug/L), which is about 1 ppb. Source
1 mg/Liter of 2,4-D is the maximum allowable level this product can exist in our drinking water.
A random selection of Municipal reports listed below have virtually ZERO detectable levels of 2,4-D and not 1 exceedance was found.
Tavistock 2007 < 0.1 ug/L
Leamington 2008 < 0.19 ug/L
MindenHills 2006-2009 <0.15 ug/L
Minto 2007-2009 0.2 ug/L
Toronto 2007-2008-2009 0 ug/L
Waterloo 2003-2008 1 ug/L
Drinking-Water Systems Regulation Ontario Regulation 170/03
Every Municipality offers an Annual Drinking Water Report to the public for free. Via phone,mail,library,newspaper,publication or internet.
Here is an example of a 2009 Toronto Drinking Water Report: