Is she spayed?
Is she overweight?
Many female spayed dogs tend to gain weight. This can create additional folds of skin around the urethra. In addition, many females spayed early can have a smaller than normal vulva that tends to sink into the surrounding skin creating more folds in the area. These folds trap moisture which can lead to skin dermatitis and help bacteria flourish in the area which can and does lead to frequent urinary tract infections. You can read about this here:
You will want to keep the area clean and dry. Benzoyl Peroxide wipes are also effective for cleaning the folds as well and to keep bacteria in the area down. Some vets will recommend using baby wipes. Make sure she gets enough fluids and adding small amounts of cranberry juice or vitamin C to her water can help keep UTI's away. The following page discusses vitamin C as well as some other suggestions.
So if your girl is a bit overweight, getting her weight down can help prevent excess folds in the vulva area which helps. If the infections continue to occur you may want to ask your vet about vulvoplasty as a solution. You can read about this here:
You can see what is involved in the surgery here: It is graphic.
Hope this information is helpful to you.
Urine that is more alkaline is considered basic and if a dog has been drinking more which they do when they have urinary tract infections, then the urine does become dluted. The following site explains the reactions resulting in alkaline and diluted urine in relation to urinary tract infections and stone formation.