Welcome to the Bunnings Workshop community @patel. It's great to have you join us and many thanks for your question.
You'll need to provide some more information and perhaps some pictures in order for us to give you any specific advice on your issue. Are you able to get to the leak, how much water is leaking, what type of pipework is it and is it doing any damage?
If it is one of your solid copper pipes transferring water around your house I would advise having a plumber come and have a look at it. You certainly don't want any water getting into the timberwork of your house and causing damage to it.
We look forward to hearing more information about the issue and assisting with advice on how you can go about fixing it.
If the pressure limiting valve has never leaked before then I would suggest that it is faulty and needs to be replaced or there has been a sudden increase in pressure within your pipework. It would be more likely that the valve has simply failed and needs to be replaced. I would advise contacting a licensed plumber to fix the issue.
Please let me know if you need further assistance or had questions.
I apologise for the delay in my reply. How did you go with the plumber? You might want to get a quote from a couple of plumbers to compare prices. The pressure relief fitting on its own will cost around $100 and then the cost of installation by the plumber on top of that.
Please let me know if we can be of further assistance or if you had questions.
That sounds like a reasonable price to pay.
We look forward to hearing about what other projects you have going on around you home and garden and would encourage you to let us know if you ever need assistance or have something to share with the community.