Possible Clues:

• They all go to waste when it's wet at last
• Saps of energy
• At last it's wet, but all goes to 11 down
• When it's wet at last, it all goes to waste there
• When water gets into them it all goes to waste
• When at last it's wet, they'll carry it away
• They carry off the water that comes down inside them (6)
• When it's wet at last they're all running
• Empties
• Tuckers out