Like Bangkok, Chiang Mai, Thailand's second largest city, seems to have open sewers that people connect to, illegally or legally. Other people seem to have there own underground seepage pit that their toilets are connected to. This could be problematic as there are a number of people on wells, even in the densely populated core. Supposedly there is a city connection, but delivery pressure can be irregular during peak hours so many people have elevated tanks to maintain pressure throughout the day.
I did run into one waste water treatment plant that supposedly treats the waste from Chiang Mai University and hospital, which is part of the medical school. However, in the one photo that I managed to snap before being told to leave showed that the primary clarifiers were completely filled with sludge. This means that treatment cannot continue. This was confirmed when we saw the outfall dumping raw looking sewage into another open drainage.
Once again bottled water and RO fillup stations are widely available throughout the city.
