My partner's 83 year old grandfather has been diagnosed with UTI's off and on for almost a year now, how long until he ends up with a kidney infection?

My husband spent most of a year in and out of hospitals with urine infections requiring IV antibiotics.He had kidney stones which the dr could not operate because of blood thinners.
Finally they did take him off the blood thinner and operated.
The night of the surgery he had a heart attack and was rushed to the hospital for stents and to get back on the blood thinner.
His urologist retired and the new young dr put him on sodium citrate and citric acid( rx) and now on cranberry tablets.
It has done wonders for all those infections even though he still has kidney stones.
you might ask the dr about that.

Most UTIs don't travel to the kidney. As someone who a few decades ago got them very frequently, had only one in my lifetime go up to the kidney. That isn't to say it can't happen and great care should be taken to get it treated. Was just told by my doctor that these days they don't even treat infections without symptoms and consider as many as three a year quite the norm. Golly!

Best of luck.

An untreated UTI will most likely result in sepsis. Once sepsis shock sets in (3rd stage of sepsis) it can be a matter of 12 hours or a few days. I'm so sorry they cannot treat his UTIs... may your partner receive peace in his heart.