First of all, you have to make sure that it really is a leak in the first place. What do you think is a leak, may be something else. There are actually three main causes of water loss from swimming pools and they are:

1. Swimming pool plumbing leaks

2. Swimming pool shell leaks

3. Normal evaporation or excessive splash

So before you go any further let's rule out number three in the list above. It's important to do this, because actually the sun can evaporate quite a bit of water from a pool on a daily basis without your realizing it, and swimmers can splash a lot of water out of a pool too..

To find out for sure if the water loss is due to evaporation or not, take a fairly large container and fill it with water and place it on the first step of your pool. Then remove enough water from the container so that the water level in the pool and in the container is exactly the same. Now leave the container there for a couple of days to see what happens with no one using the pool in the meantime. If after a couple of days the water level in the pool has gone down, and the water level in the container has gone down the same amount, then you know that the water loss you are experiencing is most likely just evaporation due to the sun.On the other hand, if the water in the pool has gone down farther than the water in the container, then most likely there is indeed a leak in your pool somewhere.

To find a pool leak, the first place to inspect is around your filter and pump. Do you notice any water spots or damp areas there? If so, try to trace back where the water is coming from. Very often, it will be a connection on one of the pipes in this particular area.You may need to turn on the pump for a while and observe it to see if any leaks develop while everything is running. If the leak begins to show, and you feel comfortable with repairing the pool plumbing, then this is a job that you may wish to do yourself. However, for most people it will be a job that is best left to a pool professional.

If no obvious leaks can be found in the plumbing, then perhaps the leak is in the shell of the pool itself. And in this case, it's almost always advisable to leave any of this type of work up to a well-qualified professional.

As you can see, finding and repairing swimming pool leaks is usually just a matter of eliminating possible causes until you find the real problem. Once the problem is found, your final decision is whether to fix it yourself or pay someone to do it instead.