The first thing you must consider when trying to decide when to call a plumber is deciding if a plumber is really needed. Sometimes people get in a hurry to call a plumber when they could actually take care of the problem themselves. There are a few things that can be done before you make that call.Depending on the problem at hand, there are a few things that can be checked or done before calling a plumber to save you a lot of money, and not waste the plumber's time that he could be using to help someone else.If it is a toilet that does not work, depending on the situation, it could be simply plugged up. If the toilet flushes, but it does not go down or gets close to overflowing, the toilet is most likely plugged up. There is a simple solution to that; you need to plunge it out.You simply take a toilet plunger and put it down into the toilet, covering the hole in the bottom, and move it up and down to create suction. Be careful to keep it low and in the water or it will splash you. After a few minutes of plunging, try to flush the toilet. If it flushes, congratulations, you fixed the problem!If it still doesn't flush, then you may have a bigger problem than a simple plug. It could be plugged further down, or the toilet may be broken. This may be the time to call a plumber, to see what the bigger picture is with the toilet.With sinks, it is a bit different. If your water will not come out of the faucet, there could be a few problems that need to be checked out. The first thing to do is to see if the water accidentally got turned off. There are turn off handles under the sink. You need to check to make sure they are turned on.Another problem that could affect the water supply is the water supply itself. The pump to the well could be broken. Of course, if you have city water that is not the case, but country homes have wells.If your sink is backing up, you could try the same technique as you would do for the plugged toilet; use a plunger to try and unclog the sink. If that doesn't work, you could try a commercial liquid drain opener. It may take a few hours to unclog the sink. If that doesn't work it is time to call the plumber.When you decide to call a plumber, you can look in your local yellow pages for a listing of plumbers in your area. Another resource is to call a hardware store or a plumbing specialist and they will either help you or give you a referral.Sometimes friends or neighbors have found someone that they know and trust and will give you the name and number of their favorite plumber. When it comes to the health of your plumbing; if you can't do it yourself, then a professional will have the knowledge and skills to get the job done right!