Staying healthy in Mexico City - do's/don'ts

Well, I last visited Mexico City in 1977...... At that time it was bottled water only and hot coffee was thought to be okay. We washed all fruits and vegetables with a chlorine wash at that time before eating them. Even brushing your teeth had to be done with bottled water. Things may have changed in 46 years :)

I’ve been to CDMX three times, in addition to visits to Oaxaca, Morelos, Puebla, Yucatán, Baja California… I’ve never taken significant precautions and never had any problems.

Food borne illness is not a threat to your health as much as being a victim of violent, non-violent or petty crime in Mexico City according to the USA government
https://travel.state.gov/content/travel/en/traveladvisories/traveladvisories/mexico-travel-advisory.html

Ok. Good to hear. Looking forward to visiting this amazing city! Thanks

The last time I was in MX I took Betaine HCI and Charcoal and ate fresh salad greens and everything else and had no issues. Drinks sold in cans and bottles are fine. If you make coffee or tea use bottled water.

I was Born in Mexico City and visit my family down there every Christmas.

Do not drink tap water, but only bottled ones. Hot coffee is ok as the water has been boiled.

If you make salads, go into any supermarket and buy a small bottle of “desinfectante”. Add two or three drops of that stuff to water and wash your veggies or greens in that solution.

Do not eat at any of the food stalls on the street, but rather go into formal restaurants.

If you take a taxi, make sure to have find a “sitio” (taxi base) that you can call for a ride. Uber is fine, but some drivers are awful.

Enjoy Mexico City!

To echo some of the good advice from am888:
Rely on bottled water only - and that includes the water you use for personal hygiene (brushing your teeth for example). One of our own lessons learned was to take special care while in the shower - it's easy to inadvertently ingest a little of the water if you're a bit careless. My wife can attest to that one.
Though we usually enjoy self-catering while on travel, the hassle of disinfecting fruits and vegetables got to be more of a pain than it was worth for us, especially since restaurant food was cheap enough to make the effort to save a few pesos largely meaningless.
I'd stick with bottled water for coffee too.
We never had any issues with food or drink in any restaurant or cafe - they typically do a pretty good job in that regard.
Do bring along some anti-nausea medications. We usually toss in some Pepto tablets just in case - better to have it and not need it than the other way around.
You're going to love Mexico City - it's great. As with any large city there are areas to be avoided however so do your homework before your trip to familiarize yourself with the city. We found the Metro to be a cheap , efficient, and safe way to move around the city. Glean whatever local knowledge you can from your hotel's concierge regarding any safety or security concerns you may still have upon arrival.

Thank you arn888 and Robert. Good advice

There are recommendations to use pepto bismol prophylactically.

see:
Jane Brody: https://archive.nytimes.com/well.blogs.nytimes.com/2016/02/22/staying-healthy-while-traveling-the-globe/
the source: https://pubmed.ncbi.nlm.nih.gov/6985681/
Frommers: https://www.frommers.com/tips/health-and-travel-insurance/pepto-bismol-for-travelers-diarrhea
The Frommer's article also has some advice on who shouldn't take it.

from Brody:

Before every meal, we each chewed one pink tablet of bismuth subsalicylate (sold as Pepto-Bismol and various store brands). I have used this preventive since first reading about it in 1980 in The Journal of the American Medical Association in a study led by Dr. Herbert L. DuPont, an infectious disease and travel medicine specialist at the University of Texas, Houston. The study described how using these tablets greatly reduced the risk of traveler’s diarrhea among American students traveling to Mexico. In a subsequent study published in 1987, Dr. DuPont and colleagues reported that two tablets chewed four times a day reduced the risk of developing diarrhea by 65 percent. (Each tablet contained the standard dose, 262 milligrams of bismuth subsalicylate.) I have relied on these tablets, albeit in a lesser dose because I’m a lot smaller than average, during trips to Vietnam, Thailand, Peru, Indonesia, India and Nepal, and never got sick despite eating salads and peeled fruit, which one is warned to avoid. In fact, in India and Nepal, my traveling companion, who also took the tablets, and I were the only ones who stayed healthy even though the others in our group assiduously avoided those no-no foods and we did not.

We just returned yesterday from our second trip to Mexico (not Mexico City, but for the most part, it's the same around the country when it comes to water). On this second trip, we did get sick. We followed the same precautions as last time: We only ate at well-reviewed places, only drank filtered water, and brushed teeth with tap water.

We didn't get sick until the end of our 4 night trip. You should be fine ordering ice -- from what I've read, Mexicans all buy bagged ice from the factory, and even Mexicans drink filtered water, so they would not serve you tap water (or ice made from the tap). I would honestly still just avoid ordering from someone who looks like they may have sanitary practices that my stomach may not handle (e.g. the vendor who leaves the tub of mayonnaise out in the sun all day).

If you want to play it safe, follow the other tips at avoiding street vendors, and brush teeth with filtered water. I've read 50/50 mixed reviews about whether it's okay to brush with tap water, so we have chanced it, but in the future we will use filtered for teeth brushing. We didn't get "very sick", only mildly so, so it's possible this was our mistake.

I do not know how to guard against this, but I can share that twice in CDMX I was sick (the runs, ugh) from inadequately reheated food that must have been prepared earlier in the day. Both times I was at nice enough restaurants. One was the Sanborn's in Casa de los Azulejos. All my dining companions were fine except one friend and me, who both ordered chicken enchiladas and suffered the consequences the next day. Our food must have been prepared earlier and then poorly reheated. The second time was dining alone in the restaurant of my hotel in Roma.

All I can say is, be prepared with your own toilet paper (which I know you will dispose of in the bin next to the toilet, not the toilet itself) and small change to tip the restroom attendants in case you have an emergency while on the go. Good luck!

Falling ill is always unpleasant, especially when traveling. You are wise to consider precautions. I contributed a lengthy Trip Report to this forum last October ("A Week in Mexico City ") but I only offered a few concerns regarding the daunting topic of " safety ".
Since then, a trip to Guadalajara is in the works, so I find your questions (and the replies you receive) helpful to me as well.
I had no issues with street food (so wonderfully delicious and available everywhere) but I understand the cautions stated by others.
Mexico City is so exciting and magnificent, taking precautions its a worthy endeavor.
I sincerely hope your experiences will be as pleasant as mine.

It’ll depend on the strength of your stomach and having good luck, but bottled water is obvious. And several hotels I’ve stayed at had bottled water, at least in a large container that you could refill from. Skipping ice is safer, but I’ve used tap to brush the teeth and was ok. Maybe rinse the mouth and brush with a bit of bottled to save water? And be mindful of street vendors, including salsas. The only time I had a problem was when I got chips that are sprinkled with lime juice and hot sauce. Think the lime juice was diluted with water. It doesn’t mean you can’t try things, but maybe limit quantity or be ready with meds, just in case. But you shouldn’t need to worry about any restaurants. Even Mexicans get sick from the water and restaurants wouldn’t survive if they made the regulars ill, and you might want a salad at some point. But Mexico City is a fabulous place and a great city to walk around in with amazing museums. If you have to be a little extreme to make sure you can enjoy it, they’ll understand.

Big thanks to all for your tips and insight. We will do our best but not miss opportunities to enjoy the incredible cuisine