The answer to this question depends somewhat if you are a lawyer!
The law defines what is safe to drink, for example in order to set the level of purity that water companies must attain before transporting water to you. The Guidelines for Canadian Drinking Water Quality set suggested maximum levels of each of 91 chemical contaminants that remain in the water, plus seven microbiological and seven radiological contaminants. There are, of course, tens of thousands of pollutants and contaminants that exist, but the law chooses to ignore these in the hope that none exist in a sufficient concentration to be harmful to health. This is partly an economic argument, since many of these contaminants are viewed as simply too expensive to remove – for example, the argument goes “why build costly systems for removal of radioactive particles, when it’s extremely rare for such particles to be present in water in significant concentrations?” However, radioactive Radium particles ended up in our water supply in rain, in the week following the 2011 tsunami, from the Fukushima nuclear plant, and if there are further failures at that plant you can guarantee that further radioactive pollution will follow. This is one of many examples where “extremely rare” events still have a likely impact of us.
As explained above, the law currently looks at levels of 91 chemical contaminants. In the 1970s it looked at considerably fewer, and set lower targets for their concentration in water. The law tends to be framed in terms of what is economic for water companies to produce, and it follows from this that the water we drink is close to the legal minimum quality. It also means that the water we drank back in 1970s was unsafe to drink by today’s standards. In turn this makes it highly likely that the water we are drinking now will be considered to be unsafe by future standards.
The function of chlorine
100 years ago the average age was around 35. Aside from death at childbirth, the biggest contributor to this was typhoid – transferred through dirty water. People discovered that the bacteria that transmit the disease could be killed by a number of chemicals, but the one that was considered safest was chlorine. Europeans tend to use ozone, some US states use fluorine, but here in BC (as is the case in most of North America) we use chlorine. The law says it’s ok for the water companies to leave chlorine in your water, and so they do. Does this make it safe to drink? Click here for supporting detail for why we believe that you should not drink or bathe in chlorinated water.
So what’s in YOUR water?
The answer is that aside from chlorine which you can guarantee to be present, the only way you’re likely to find out what’s in your water is to send it for lab analysis. However, that’s an expensive and unnecessary step, not least because the picture is likely to change regularly – for example the water company may change its filtration processes (for example raising pH), or if mains or pipes are cracked then the cocktail of pollutants that seep through the cracks changes over time. That said, to set up professional-grade systems optimally, you DO need to know some aspects of what’s in your water. That’s one reason why we provide a free water test for you – where amongst other things we measure the levels of chlorine, iron and Total Dissolved Solids (an objective measure of the level of contamination of your water, without breaking it down into what the contaminants are).