Morning. You have soft water...do you additionally have a water softener attached to your water lines(vegas is notorious for these)? Softened water has very high sodium content, so not only will salt buildup cause potential nutrient lockout , but it will also trick the plant into thinking it has enough water when it's actually constantly thirsty. If you can get your city water analysis that might help, also the ec ppm like mentioned. Otherwise you may want to invest in using ro water.
Best of luck happy growing.