dgs49 wrote:The lack of filtration has nothing to do with the presence of biologicals. These are generally treated with chemicals, but can also be killed/neutralized by boiling the water.
Both cryptosporidium and giardia are protozoa which at a certain stage of development are encapsulated in a cyst. This makes them resistent to chemical disinfection.
Many biologicals can live in a sand filter or easily swim through.
A cyst does not "swim", and if filters are properly calibrated and maintained they can do the job. And of course much both organisms are much larger than bacteria or viruses.
One might also keep in mind that between the water treatment plant and your dwelling place, there are thousands of feet of pipe containing sludge deposited over many years, and your drinking water travels through these nasty pipes on its way to your kitchen sink. So even if the water was 100% pure (which it cannot be) when it left the WTP, it has been compromised in the pipes regardless.
One would presume that the quality of the water once distributed would also be tested...The possibility that water quality might be compromised down the line is no excuse for not properly treating the water in the first place.
And that doesn't even consider the chemicals that leach out of the pipes themselves, even if they had been sterilized the previous day.
And all of that stuff is subject to regulation as well.
Still, anyone who is in a high-risk group can easily avoid danger by either drinking bottled water or boiling the water that is to be drunk.
In Milwaukee in 1993, a problem at a water treatment plant caused over 400,000 people to get cryptosporidosis. The implications for high risk groups are more about severity (they are more likely to end up in hospital or dead). And of course, just because a healthy person might not get sick does not mean they aren't able to infect someone else.
As we all know, toxicity is almost entirely related to DOSAGE. The human digestive system can tolerate just about anything, provided the dosage is low enough.
Because they are encapsulated in a cyst, both organisms can pass through the digestive tract without being affected by stomach acid, etc., that might otherwise reduce the virulence. It is possible to get sick from injesting only one giardia or less than ten crypto cysts. Compare that to the hundreds of thousands of bacteria that need to get inside you to cause disease, and you might be less cavalier.
But when reporter is hard up for a story, s/he can easily get headlines by writing an article stating - truthfully - that the local water supply contains arsenic, bugs, heavy metals, or what-have-you.
There are reports coming out the wazoo about the issues with SF's drinking water. This isn't someone in search of a cause. The SF water utility has been doing PR on steroids for years to assure people that they are on top of it.
What it comes down to, of course, is money. They don't want to spend the hundreds of millions of dollars it will take to install filtration systems in the affected plants.
There are lots of better things to worry about than infinitesimal quantities of bad stuff in your drinking water.
It's easy to say until it turns out to be enough to make you sick.
rubato wrote:If the water supply really was as unsafe as the OP suggests there would be an epidemic.
There isn't.
Find a real problem to address.
Does a
reported rate of disease four times higher for crypto and over five time higher for giardia, compared to Los Angeles, give you any cause for concern?
It's interesting, in that same letter it says that the new UV system they are wanting to install will allow them to reach the target of reducing the levels of giardia and cryptosporidium by 99%. That sounds great, except the EPA standard for giardia is 99.9%. Was this an error in drafting the letter, or a Freudian slip? One would hope they wouldn't be planning to allow levels of organisms ten times the allowable standard.The way they handle it in the
annual report is interesting. When they talk about the types of contaminants in drinking water, they conveniently don't mention protozoa among the microbial contaminants. They say in the narrative that they detected "very low levels" of cryptosporidium, but they never said what those levels were, justifying hiding the information because of the uncertainty of determining whether the samples found were alive or dead. BUT they felt it necessary to include TWO warnings about the potential dangers of improperly treated water on the immune compromised. Hmmm, according to what I've been reading, that's only a requirement in cases where there has been a breach of a standard. Are they just taking out insurance in the event that something may go wrong in the future, or do they know something now that they aren't telling?
