Mine stopped working after less than a year, I bought another one that also stopped after a year or so.
As one of the founders of ECOSERVE my opinion is admittedly biased. Nevertheless, here is some general info that I hope is helpful:
No water purification system that is accessible to an average home owner is designed to deal with the extreme water conditions we have from Cabarete to about Perla Marina (parts that receive water from the Catalina aqueduct). The brown or carrot-colored water that comes through when it rains heavily for a few days will overwhelm most home water filtration systems with sediment in a matter of weeks. The filters will get stopped up and require changing.
That said, most people who have bought systems on their own and tried to manage them end up frustrated as the quote above shows. I would definitely warn against buying a system abroad and trying to manage it on your own (unless you have a lot of patience and some plumbing skill). You will need to change filters periodically and, in the case of UV systems, clean the hardness off the UV sleeve. You will get much better results buying locally from a company that offers ongoing service and has replacement filters and parts in stock.
UV systems do require a certain level of water clarity to ensure proper UV dosage. This is why most systems come with two layers of pre-filtration to make sure the water is clear by the time it runs through the lamp. The problem isn't typically that dirty water gets through the system. The problem is that, when the pre-filters get full, the water pressure drops in your home and you need to change those filters. Your local water purification company should provide this service for you.
I hope this is helpful.