You may be thinking of not hiring Plumbers and instead work on things all by yourself. There are simple fixed you could do on your own like, changing water supply fixtures like faucets, knobs etc. but if the problem gone a bit complex then it is just necessary that you hire a professional plumbers.
There are different types of plumbers you could get services from. It is important that water supply up to water disposal is properly processed. If the issue is somehow simple then you could work on it all by yourself. There are basic plumbing tools you could check on hardware or local retail shops which could help you perform simple fixes.
If you want to work as your own plumber, there are a lot of tutorials you could check online which will show you hoe to properly replace faucets and simple water pipe leaks. Do not settle though for temporary fixes as the issue may become graver if issues are not worked on properly and patch all issues permanently.
There are simple clogging issues that do not require professional plumbing fix. There are simple tools that could help you remove clogging like different commercial solutions you could check out online and plungers etc. Expertise is not necessary to work on those simple clogging, reading on the instructions on the solution label is necessary and as well as proper use of plungers.
Seeking help from professionals and certified plumbers is highly recommended if the issue you encounter is more complex like pipe cracks underneath and hard to reach clogs. It is best if this will be worked on by professional repair plumbers to ensure that issues will be provided with the right solutions. Any wrong fix could serve graver issues and that is not a great idea at all. Any issues on pipes if not worked on or troubleshoot right will serve bigger problems and actually bigger expense.
The problem may differ thus expertise from plumbers is highly needed. They are the best people to work on more complex issues on you pipelines etc.
You may be thinking that plumbers work is only limited to water. There are gas plumbers that you also need to call on, if you experience any issues with your appliances being run by gas like heater, stoves etc. Problems related to gas plumber responsibilities, may it be as simple as changing of stove plates, heater knobs should only be done by plumbers Sydney and no one else. The risk it may serve if not correctly installed or fix is fatal thus expertise is required.