The Water Castle by Megan Blakemore

Ephraim's father has had a stroke and his family have picked up and moved to their ancestral home so the father can be near a special doctor.  The home is actually more like a castle, and was built with money earned from selling bottled healing waters.  Ephraim's great-grand-father had spent his life searching for the fountain of youth.  Ephraim becomes obsessed with the hope that he can find the miraculous water and heal his father.  He is aided in his search by two kids whose families have been mixed up with Ephraim's family for generations.  As they work together, they begin to heal the rifts between their families, and within their own lives.

The fun thing about the book is that the reader doesn't know whether the waters really do have healing powers or not.  The author switches from modern time to historical time throughout the book, gradually giving hints as to whether Ephraim and his friends are on a wild goose chase or not.  The weakness of the book is in the science.  Blakemore tries to suggest a scientific reason that the water might heal people, but anyone with any experience with chemistry will immediately see some serious problems with the explanation.  There is some interesting discussion about whether an elixer of life would be a good thing or not, but it is a little heavy handed.  Of course, the best treatment of that topic is in Tuck Everlasting by Natalie Babbit. Still, overall this was a fun book, and kids will probably not be bothered by the little weaknesses. (344p)