A leaking PVC pipe on the side of your house can be due to a few different things, some of which are normal and not to be concerned about, while others may indicate a problem. Understanding a few potential sources of the water can help you narrow down likely culprits and ascertain whether you have something to worry about.
Central Air Conditioning
The most likely culprit of a leaking PVC pipe on the side of your house is a central air conditioning condensation and evaporator drain. When your air conditioner runs, it not only reduces the temperature of the air in your house, it removes excess humidity to make conditions more comfortable. This water has to be drained away from the unit and is usually done so via a length of PVC pipe outside the house or a hose. If you have central air and it has been running the last couple of days, this may be the source of your water leak, and you need not be concerned.
It is possible what you are looking at is a damaged spigot, where a garden hose would normally be attached. If you are a new homeowner and are not familiar with the locations of your hose spigots, you will have to get under your house or check your basement to trace where this PVC pipe emanates from. If it is indeed a broken spigot, cap it using a PVC cap until a more permanent fix can be made.
Oftentimes in houses of newer construction, a drain access point, or sewer access point, will be installed in the main sewer line of the house. This access point is located close to where the drain leaves the house and is intended to be used in case of a clog, for a plumber to feed a snake through and dislodge any debris. It is possible there is a clog, and this drain is now backing up and overflowing.
If you have a cellar, and the PVC pipe you are looking at is of a size greater than 1/2 inch, it is possible it is a sump pump drain from the basement. Sump pumps are used to prevent water filling up in basements during heavy rain. If it has been raining for the last couple of days and you are seeing periods of heavy flow emanating from the pipe followed by dribbles, it is possible this is a sump pump drain.