Shower and drinking water filters

I get a lot of questions about water filters, but I don't know much about them. So this is just a page of my notes so far, with links to other sites if you'd like to dig deeper. Feel free to leave comments with additional information for other visitors.

Chlorine and chloramines

Different municipal water supplies will use different germicides, so if you'd like to reduce your exposure, it's useful to find out which type your utility company uses.

For utilities that use chlorine, it sounds like they aim for a few parts-per-million of chlorine at the tap. They don't want so little as to let microbes live, but not so much as to cause direct health issues. Those levels are probably in the range that many people can smell and taste, so tasting and smelling your water before and after filtration could be useful.

"Aging" water to remove chlorine and chloramines

It appears that the common technique of "aging" tap water (leaving it in an open container for a long period before use) is less convenient than you'd think: it may take days to significantly reduce chlorine levels.

Boiling the water can be more effective, with significant reductions in a couple hours for chlorine. However chloramine content might take a day or more of boiling for significant results.

Water testing

There's several approaches to water testing depending on what substances you want to identify:

Where should the water be filtered?

I was surprised at the idea that some of the riskiest exposure to chlorine and chloramines may be from showers and baths rather than ingestion. Chris Kresser's article and references have more information about that.

Whole-house filters are very expensive, and I don't see a strong reason to use them instead of smaller filters at the bath and tap.

Shower filters

It sounds like vitamin C based filters are probably the ideal option, but they're expensive. I only care about chlorine reduction (my utility company doesn't use chloramines), so I'm considering buying the Sprite HO2-WH from Amazon. It seems reasonably well-reviewed for the price, and is NSF 177 certified to reduce chlorine by at least 50%.

Drinking water filters

I haven't yet bothered to buy a drinking water filter (I don't consume much water, and already age the water I use), so I don't have any product suggestions. However, the Environmental Working Group has a large database of filters where you can choose your objectives to filter (heh) the results.


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