Answer: It's really difficult to diagnose a plant problem without seeing it. You've included some clues, though. Frost can damage the crown or growing point of the palm. Fronds sometimes can protect the growing tip, but not always. The only way you'll know is if you inspect it to see if it is still green and alive. Reclaimed water can contain excessive amounts of minerals which might build up in the soil. So, either of these conditions might be what is causing distress with your palms. You might want to have a palm tree expert examine your palms. I hope they recover!
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