How was the purple paint removed from the centipede's body?

From the text:

Three seconds later, the whole underneath of the cloud seemed to split and burst open like a paper bag, and then -- out came the water! They saw it coming. It was quite easy to see because it wasn't just raindrops. It wasn't raindrops at all. It was a great solid mass of water that might have been a lake or a whole ocean dropping out of the sky on top of them, and down it came, down and down and down, crashing first onto the seagulls and then onto the peach itself, while the poor travelers shrieked with fear and groped around frantically for something to catch hold of -- the peach stem, the silk strings, anything they could find -- and all the time the water came pouring and roaring down upon them, bouncing and smashing and sloshing and slashing and swashing and swirling and surging and whirling and gurgling and gushing and rushing and rushing, and it was like being pinned down underneath the biggest waterfall in the world and not being able to get out.

"Look at me, look at me!" shouted the Centipede excitedly. "It's washed me clean! The paint's all gone! I can move again!"