Now that summer is near, I am finding that, in the afternoon (if the sun is out and the outdoor temperature is in the 80s or above), the cold water from my kitchen sink tap is warm-to-hot for 30 seconds or more before it cools down. The kitchen tap is on the other side of the house from the cold water manifold, so it is a long run of pipe. I measured the temperature at the tap with a kitchen thermometer today-- it was 130 deg F for 10 seconds or so, which seems really out of line. I haven't seen this problem mentioned in other postings to this group concerning attic routing of water supply lines.
Is this normal for attic-routed cold water supply lines in a hot climate? I have a hard time believing that the water could pick up so much heat. My attic has passive ventilation, with no soffit vents. Would improving attic ventilation result in a big improvement? Or is the plumbing work defective somehow?