📰safety-rules
Chemical hygiene
Following up on digital hygiene, I wanted to write up my (evolving, opinionated) guide to chemical hygiene. I keep ranting about this topic to all of my friends recently (you can tell I'm really fun at parties), so I thought it would be worth writing it up to have it all in one place/url:
Water
Starting out with controlling your water system, which is the easiest in terms of concrete, high confidence recommendations that in my experience still only Reverse Osmosis - the gold-standard Point of Use water filtration system, with a remineralization post filter. Ideally install an under the sink system, but fallback to countertop systems is ok. Brita and other basic filters are not good enough to adequately filter your drinking water.
In addition, install a whole-home water filter (usually sediment+carbon, not Reverse Osmosis, that would be impractical), to enjoy cleaner water in your entire home, including shower, dishwasher, laundry, etc. If that's too expensive or impossible (e.g. you're renting), at least install a shower filter.
Avoid drinking water from water bottles, certainly from plastic bottles but also in general. You cannot control that supply chain, both during collection but also during delivery (especially light, heat).
Avoid drinking tap water, it's a lot less clean than you'd think (it is relatively poorly treated centrally and then it has to be delivered to your home through undefined pipes) and, with proper dental care, includes unnecessary and possibly mildly harmful "public health" additives especially and controversially fluoride. Example fun study: people living near golf courses (which are heavily treated with pesticides) show an increased risk for Parkinson Disease.
Water is the easiest section in this entire article because it has well-understood ways to spend $/risk reduction compared to a lot more complex categories we'll see later (food especially). I would recommend contacting a company in your local area to install both a whole home filter
karpathyDec 18, 2025