How long would you have to have an untreated uti before it affects the kidneys?

Variable: Depends upon bacterial species, some are like mini- caterpillars, presence or absence of bladder reflux, or if reflux develops as result of ureteral valve becoming rigid as result of bladder inflammation. Other factors can be host resistance to infections depending on such things as bladder emptying, immunoglobulins ; quality of wbcs. Thus UTI can affect kidneys from as early as.