Talk to Cipi's (Tech Transylvania) dad... he builds them. He maintains the equip for WASA, lot's of the island's resorts. Upside of what he does is that he'll use as much non-proprietary parts as possible. In other words, if a belt wears out, you don't have to Fed Ex a $100 belt down from Miami, you can buy a belt at Morelco or an auto repair shop. Membranes and such are the same as in commercially built systems. Have everything as manual as possible... bells and whistles and electronics just break. And plumb it to both your well and the sea if possible. The former is easier on the membranes, the latter, well, it won't run dry in the dry season... if it does, you got bigger problems to worry about!!!