Mr_Moggie wrote: it seems that the pipe is blocked and there was a slight leak.
Where was the leak?
Mr_Moggie wrote:Would it be worth taking the piping out and putting it in a bucket of water to see any air bubbles come out - and if so, buy new piping? Or is it more likely a blockage from the hard water?
That would work for finding a puncture in an inner tube but as the tubing isn't airtight I don't think that will help much in finding a leak. If you remove the tubing you should be able to see if there is a blockage or any cracks. If not, pour water in one end of the tubing and see whether it comes out of the other
Have you tried pushing the pump and seeing whether any water comes out of the water bottle and up into the tubing? The non-return valve might have stopped working. This is the small pastic bit that fits on the end of the tubing which goes into the water bottle. It can sometimes fail meaning that the water is unable to pump round up to the washer jets. Cheap to buy - your local motor factors will probably have one. I'd try this first before removing the tubing.
If the non-return valve is working OK the water pump could have packed up so you might need to get a replacement one.