I doubt that its cheaper to buy water plus you dont know what shithole they took it from
For us, this is the main problem with truck water... I don't know what happened, but ever since the city management in POP changed last year (Coraaplata including), we've had zero problems with water... Before that we had to resort to water truck every few months... The problem was not getting one, the problem was not paying for it (500 pesos), the problem was the quality... Our cistern was contaminated on each truck load... Our neighbors, who have lived here for more than a decade, advised that in particular because we have small kids, please try to rationalize as much as you can (we do) to avoid getting water truck... You can never be certain of the quality... Ever since we have not used one single truck load of water, our cistern is always crystal clear with just a tiny bit of sediment (that we can vacuum) in the bottom...
EDIT: we get water from Coraaplata two days a week, when they completely fill the cistern... That is not 24/7 obviously, but we get way more water than we would need... They have also been 99 % regular ever since the city management was changed...