Last week our water froze which means we have to carry in water and flush the toilet with a bucket. It's amazing how much more efficient the real flush is compared to using a bucket. I have experimented with all angles and flow rates but I can't beat the hundreds of years of design that went in to the WC. The reason we have no water is because the temperature has been down to -18°C and the water froze in pipe leading to our house. The interesting thing was that the water didn't freeze when it was -18°C but some days later when the temperature rose to about -1°C, apparently that's the way it always is (Why does everyone always tell you these things after the event) which is quite strange. Why should the water freeze when the temp rises? the only explanation I have is that its to do with air currents but that's as far as  have got. I can see an EE coming out of this. The only alternative explanation I have heard was that the rising temperature forces the coldness back into the pipes but I'm not saying who it was that said that.