Ask around. Ask your friends, ask your neighbors and get referrals. Nothing is more powerful than the testament of someone who has had a local plumber in their home and can speak to his/her capabilities.
Look for a company that offers emergency services. If something happens after hours and your bathroom is flooding, you need someone right away, not after 8 am in the morning. The best companies will offer a rapid service for Trustworthy plumber their clients.
In order to summarise, the best plumbers to call out to repair your condition will be the plumbers who are able to get to you the quickest, provide you with a reasonable cost and have the expertise to carry out the job and complete it correctly. Everything else is actually not worth the work.
When planning major renovations, make sure you put a great deal of thought into the design and layout of your work. Make sure you check with your local council as a lot of work requires building permits (including plumbing). Please make sure if your work requires a permit, don't be tempted to get the work done without one, as you may end up in court.
Like knowing where your electrical panel is located, it is just as important to know where the valve for the main water drain line repair to your home is located. Also, knowing where the water valves for individual fixtures can help keep small leaks from becoming major repairs. Start by turning off the water for the individual fixture near the affected area. If that doesn't work, or your issue is a busted pipe, turn off the main water service. The main water valve is usually located outside in a box in the ground. Turning off the water main will stop the flow of water to your home and thus preventing further water damage.
Sometimes repairs do not need to be immediate, but they should be quick. When you do not need emergency repairs, but cannot wait days for help, you should find a plumbing company offering same day services. This means you can call in the morning and have someone there to make the repair within hours. Since some companies do not offer emergency services, same day service may be the next best thing, so you should look for this offering if it is the best your Local plumber has.
The first step is to find out the cause of the dripping tap. This is generally caused by a worn out washer. As per various water authorities, only licensed plumbers can work on water infrastructure legally which includes all fixtures and fittings within the home including the dripping tap.
Identify the source of the clog. You can find the source by running water in other sinks in the house. If all drains back up, then the source of the clog is in the soil pipe itself. Call for service to root it out. If it's the toilet, plunge it. If it's only one sink drain, check underneath for a clean out trap. You can unscrew the plug at the bottom and pull out the clog.