Water emanating from a PVC pipe on the side of your house may have a few sources. PVC is used in newer construction homes for drain, water, and ventilation applications. It is never used for natural gas or oil, and as such these sources can be excluded. Your PVC pipe is almost certainly a drain and you have a few things to consider that can help identify the source.
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Some homes contain drain access pipes, which can be of PVC, and are intended for use if a clog forms in your main drain. They tie into the drain that leads out to the street sewer towards the end of the home sewer line. These are always sealed over, however, typically using a threaded cap end. If your PVC pipe has threads, but is missing its cap, you may be looking at a drain access point that has had its cap removed. Check your basement or crawl space to see where the pipe ties in and cap it if necessary.
Air Conditioning Drain
If you have a central air conditioning system, you may be looking at a condensation drain. When an air conditioner cools the air in the house it also removes moisture from the air. This moisture is collected and allowed to drain away from the air conditioning unit to prevent damage to the unit, and the area surrounding the unit. These drains are often made of PVC and will slowly drip on the side of your home. If the water is accumulating and harboring mosquitoes or becoming unsightly, consider attaching a hose to the PVC pipe and running it to drain somewhere more appropriate.
It is possible that your PVC pipe is actually a broken spigot. If you have a new home, and are unfamiliar with outdoor spigot locations, a trip is in order into your basement or crawl space to see if this PVC pipe is tied into your water lines. If so, attach an outdoor spigot to the PVC pipe. You can buy PVC connections and hose attachments at most any hardware store, and install them using PVC cement. They do not require soldering or substantial plumbing knowledge.
It is possible, although unlikely, that you are seeing a drain for a sump pump that is placed in your basement. These drains are typically at least 1 1/2 inches in diameter and are used to drain water that is pumped from your basement outside, to prevent basement flooding. If this is the case, and you have had a period of substantial rain, you are going to need to attach a hose to this PVC end and have the water drain elsewhere. Water draining directly next to the home will simply find its way back in to your basement. Drain the water at least 25 feet from the house foundation.