For example, Jakarta has a water treatment facility, but every tourist gets stomach illness there. The reason is that industrial facilities siphon off the treated water, and by the time homes and hotels get any, it's untreated.
To give you an idea how bad it is, tourists generally don't drink tap water, but they still get ill from the washed dishes, or not closing their mouth in the shower.
(Bali can always find money for road construction (they built two impressive underpasses in the last 6 years), but never enough for a power generation plant, so has continual brownouts.)
Unless the facilities are adding dirty water to the pipe to push pressure back up after they remove it? But even then, unless they routed the pipe from the water treatment facility to the industry first, only the areas downstream from the industry would be affected.
More likely is that the water is not being adequately treated and/or that the infrastructure is not built/maintained and the pipes are leaky.
My guess would be that the treatment is to minimum spec and that there are leaky pipes which allow for contamination. It is hard to maintain pumped water pressure if there are brownouts.
Even in the US I know of cities that have had boil orders because the treatment plant couldn't keep up and they pumped in untreated water. The cases I know of the unfiltered water made it in via weather events (the treatment plant is on the river and it flooded. Also a case where the power went out on a big surge and so they hardwired the pumps to the well bypassing treatment until the treatment controller boards could be replaced.)
Most people don't know that pure water is an insulator.
However, in a practical sense that's ok since it's unlikely any pool of water is pure.
So for safety reasons involving electricity, one has to assume that any pool of water can conduct electricity.