It is worrisome but it also depends on where you live. I see no problem with competing private water companies in the north east or elsewhere where water is abundant. But I do see a problem with it in an area such as the south west. For several years now I've been following the tragedy that has been happening across Nevada, New Mexico, and Arizona as all their aquifers deplete leaving the ranchers with fewer and fewer places to water their cattle while Vegas continues to have its nightly water shows....in the middle of a desert.
More practically though the article you shared would just be one private owner transferring their interest to another private owner. The west has always had much stricter common and statutory land use controls over water then other parts of the country, for a good reason.
Parts of the country already have private water companies, like much of New England. In Boston it costs about $65 per month for 12,000 gallons of water (family of four each using 100 gallons a day). Seems expensive, right? Especially when compared to Vegas at around $50 per month for 14,000 gallons.
The difference in cost is largely due to Vegas's system and pipes being fifty years old while the Boston system is 100 years old. Things need to be replaced, fixed, and modernized so the water is more expensive to pay for those needed changes rather then using taxes to do the same thing.
Privatization of water is like the privatization of anything else utility related in this country. If companies, who can provide it cheaper and more efficiently then the government can since they are for profit while the government is not, start screwing around with service, or show themselves to unable to run the system, municipalities and state govt. take their contracts away and find someone who can do what need.
With water rights in this country the government, whether local or federal, always has a future interest in the water. The owner of the water only has present possessory interest. If the current owner does something that goes against their contract or fails to meet come criteria of that contract the govt can reclaim its water rights. Keep in mind I'm talking about water distribution, not the stream in your backyard. Although, even there, you have certain duties but usually along the lines of keeping it reasonably free of debris so in the event of a storm you don't flood your downstream neighbor's property.
I don't really care what other countries do with their water.