The water here is safe to drink. It, like most other treated water, just doesn't taste good. So we buy the large bottles. Once you pay the 50 peso deposit on a 20 liter bottle, it's just a matter of exchanging for a full one at the cost of about 22 pesos, or $2.00 USD.
But there is another option we found just a few blocks from our house.
Here's how it works:
Forget or lose the cap? No problem as they have free replacements to match most major brands.
Just another little discovery to save some money. Quite popular too as I had to wait for one other person to finish before I tanked-up, and there were two people behind me. All probably wondering what the crazy Gringo was doing taking all those pictures.