I live 72k from Korat, we are soon to get chlorinated water in the village, same source as the old supply but treated enroute.

Question will the water be potable after treatment or will it still need some kind of filtering?

I would go for a charcoal filter to clean up the chlorine. anywhere in thailand , you can drink the water, but better for you to treat it first for taste and hygiene reasons.

everynow and then you will find someone away from work because their water filter stopped working and they all get the squats

The chlorinated water is great in Isaan where most 'bathrooms' have some type of large water bucket used for water storage/splashing. It's never clean enough for drinking though.

When you can get a delivery of about 100 litres of drinking water for 100 baht in Isaan, why would you bother risking anything out of a tap? Old biddies drink village water (actually they seem to thrive on it!) but nobody younger than 40 around my part of Isaan puts it in their mouth, other than for teeth brushing.

In Udon (near Ban Dung) we get 20l bottle for 10 baht. Put it on the chiller and drinking water is good.