I had a indoor RO water system dispenser and outdoor membrane type filter installed for RM1.8k. https://forum.lowyat.net/topic/2340365/+80
The dispenser has no NSF/WQA but the filters/membrane are from US with NSF certification http://www.omnipure.com/ourCompany.htm and http://www.dow.com/news/press-releases/article/?id=6205.
Nightfelix is right only the filters/membrane are certified which is to me more important. There are a lot of China/Korean filters that are substandard and NSF certification questionable.