No one needs to be reminded about the hot Texas summers.  Please get plenty of fluids during the pregnancy.  Inadequate fluid intake can cause low blood pressure, dizziness, uterine contractions, and constipation.  Dehydration also increases the risk of urinary tract infections and kidney stones.  "Thirst" is a good indication that you are not getting enough fluid.  Also, if the urine is a darker yellow, you may not be getting enough fluid.  In general, you should drink 2 to 3 liters (8-12 cups) of water per day.  If you exercise or if you are outdoors; your intake should increase.