Question
I think my pipework is leaking.  I have turned off my pump and water level not dropping now.  How do I sort out this problem as I am a novice with pond maintenance & problems.  I have koi and goldfish.  

Answer
How big is your pond?  What kind of filtration system do you have?  When the system is on, does water pool anywhere.  Where do the pipes go?  If they go to a waterfall, that could also be the problem is the water is diverted outside the pond.  How old is the pond?  If it's new, it's more likely that a pipework problem is afoot.  You have to analyze each step from when the water leaves the pond to returns.  I don't know what parts you have.  Did you build the pond or hire someone?  If you hired someone, they should guarantee their work and come fix it for you.  I hope you can figure it out!