If it's fasting and detox you the place to go is in Trawas outside of Surabaya East Java. It's a place called PPLH Pusat Pengembangan Lingkungan Hiddup (Center for building/rebuilding life)
It is a non religious retreat type place in the mountains with the most beautiful bungalows and restaurant that sells mostly the organic foods that they grow there or from around the mountain area close by. There is no tourist stuff anywhere nearby and veryu few westerners go there. Near by there is an ancient Hindu temple and pools and also not far away are some hot sulphur pools that are very good for the skin etc. Last time I stayed there was for a week with my wife and two kids transport, food and accommodation cost me Rp400,000 which is approx AUD $55 that was quite a while ago now and I would say it has doubled in price by now but it's still very cheap but in price only. This place is magic and one of the most beautiful place I ever visited in 12 years of living and surfing in Indonesia.
It is nothing like a hotel and there are no shops or facilities anywhere near if you want this stuff you must organize a day trip back into Surabaya. If you want the deatils of this place please email/private message me and I will get you the phone number and maybe a google map.

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