We've been using tap water for teeth washing from day one - 15 years now & no ill effects. Like Rocky we use bottled water for making coffee & for cooking items which absorb water i.e. pasta. Hard veggies i.e. potatoes I boil in tap water. I wash salad veggies in tap water - I've heard some people use chloro but we don't. However we do put chloro in the cysterna from time to time so there is always a miniscule amount in any water we use. If I'm soaking chunks of coconut to keep it fresh, I use bottled water.
We never eat from street vendors, nor drink the local drinks with crushed ice from street vendors and never go barefoot other than occasionally inside the house. I do believe that over time you build up an immunity to the local bugs but it'll never be total. In 15 years I've had one case of giardia (which became 2 because I didn't get rid of it properly first time around :ermm
, one case of toxoplasmosis when I had already contracted schistosomiasis (bilharzia) from swimming in an inland lake. Chances are the toxoplasmosis would not have developed if I hadn't already got the schistosomiasis. The schisto was quickly dealt with but the antibodies show up in blood tests for years afterwards - tests this year were at long last clear - it took 12 years for antibodies to leave the system!!
There is a medicine available everywhere called Fel 6 (Fel Seis) - it's pretty much like the worming mixture we give to dogs
and many locals swear by it. The illnesses described above happened during our first few years here with the exception of the giardia which happened about 6 years ago. Cooking in our house is done by me, Mercedes doesn't cook for us at all.
We haven't experienced parasites as a huge problem at all. It's quite useful when you get them because it can be a wake up call to combat complacency
. I consider myself pretty healthy. When we were new 15 years ago an experienced expat told us we'd get 'the worms' once a year at least. It never happened.