I never drink water, in a foreign country, except at home in Munich, Germany, what I know. I always buy bottle water, for cooking, I use 5 gal bottle, who you can refill in many refill- station about 20 Pesos in Mexico.
For drink, I buy, drinking bottle water from supermarket.. horrible, I drink my coffee with a taste of chlorine...
I don't trust RV Water filters, most company use cheap filters...
I never was going sick in any country, round the world. In my US Trailer or German RV, the Water is use only for shower and wash the dishes.