Typically, kidney values aren't affected by chronic kidney disease until it's quite advanced (i.e. loss of 75-80% of function) so you could be dealing with CKD even though labs are still normal at this point. The dilute urine is a concern as are the polyuria & polydypsia (excessive drinking & urinating). Dilute urine aka low specific gravity makes for a bacterial friendly environment which is a recipe for a UTI, but may be a "complicated" UTI rather than your typical "simple" UTI.

Here is a great resource: http://www.veterinaryteambrief.com/sites/default/files/sites/cliniciansbrief.com/files/ManagingEcoliUTI.pdf

I recommend a culture and sensitivity (including sediment), abx treatment dependent upon which bacteria is found, a repeat UA after 10-14 days on abx to determine if they're working (or sooner if she is not making progress). If the UTI repeats or reoccurs I recommend an ultrasound of the bladder and kidneys to look for cystitis (bladder) and scarring (kidneys).

If you perform labs and alk phos levels are off I'd take a look at the adrenals.

I have a girl with CKD and through my own experience and research I'm not aware of a genetic component. Her mother and grandmother had no issues.

Fwiw, I do hope it's a simple UTI. Good luck!

Could also be the beginnings of diabetes. I've had 3 dogs with diabetes. Both drank tons of water and had dilute urine until the lab work finally showed diabetes. One dog had many strange symptoms that never ever pointed to diabetes, the other had high glucose within 1 month of the increase fluid intake and urination changes. Both were treated with insulin. One had to be put down due to complications(after 4mos. of treating) at at 8yrs, the other (with the worse symptoms including blindness) is still going strong and will be 13yrs soon. The third dog is now 10 and doing well.