I am insured, fortunately!
It could have been worse. It's quite a small carpet. It didn't splash anything else. And the clients were out all day so I was able to go home and get a carpet cleaner, which did a surprisingly good job of getting up the worst of it. Worst case scenario at the moment looks like I will be paying for a new carpet less the cost of the bill I was going to send for the work I did, but I haven't heard from them yet.....
So not too bad, but still it was a truly horrible moment when it happened!