Water, not so good
Turns out that water is not good for very young babies. The main problem seems to be that urination also removes not only water but sodium and other essential minerals from the body, and the baby may not be getting these replenished at the same speed (since the their only source is formula or breastmilk).
Nonetheless, if a baby is thirsty between feedings, is getting enough formula or breastmilk and does not want more, and indeed wants water when presented, then some few ounces (~30mls) are fine. This is the case with my ~3 month old son.
In some common but sadly mistaken blogs, the actual reverse of real medical information is provided, in that it is claimed babies get all the water they need in milk or formula, except when they have diarrhea. The problem with that statement is that it is wrong twice. In the case of diarrhea, water can be even more dangerous, as the baby is losing essential salts and may be becoming dehydrated.
In terms of water in formula, the standard one scoop of formula powder to one ounce (30ml) of water is all fine and dandy, but one must consider that a baby should be getting 150-200ml of water for every 1kg of body weight. Again, the amount of the powdered formula (which replenishes minerals, etc.), or other rehydration drinks.
Chlorine and Parasite Filters
Lead and other Metals
Human Milk, Cow Milk, and Goat Milk
The last visit to the doctor, he told my wife that for alternative milks/formulas people use goat milk. I was surprised as I had not heard of this, and there is no formula on the market with goat milk. Turns out, indeed, there is such a thing as goat milk formula, but it is a do-it-yourself practice (which can become complex and expensive, though there may be simpler methods of goats milk formula).
Beyond human, cow and goat milk and formulas, there are a host of others, including (apparently) sheep as well as soy and other non-animal-based formulas. With all of these it is hard to get good, accurate medical and health information about these, as the vast majority of discussions one finds are by enthusiasts and salespeople. Worse are content-mill websites who really are doing it for the money and have little to no actual expertise.
Human Milk Banking
Yes, Human Milk Banking is a thing. Apparently starting at the turn of the 20th century, there were many closures in the 1980s due to fear of HIV transmission. However, current screening protocols are sufficient to ensure safety of the milk, and so this endeavor should be encouraged. Vietnam opened a milk bank in Da Nang in 2016, though there had been a private one previously founded.
Formula, Formula, Formula
Besides the Goats Milk formulas mentioned above, it is a good idea to take a look at the ingredients of a given formula, especially mass-produced ones. The ingredients are a bit bewildering, but take a close look. The thing is, as with much of what we eat or drink, homemade alternatives are feasible and possibly the better option for a particular baby. One huge advantage of homemade formula (though there are disadvantages) is that it can be fine tuned and customized for the optimal growth of a single baby. The disadvantage of course is that it takes time, can be expensive, and getting the right formula may be difficult.
Finally, some resources for those breastfeeding includes the La Leche League.