Unless your outdoor pool is outfitted with a heater, you probably say so long to it for a few months every year when winter comes around. Since the vast majority of in-ground models are, you do not necessarily have to drain and refill yours on account of the cold season. While this is certainly not a bad thing when performed by a professional pool cleaning and maintenance company, most industry experts advise residents to keep their pools up and running year-round.
Believe it or not, but this actually puts less strain on critical operating parts like the motor and pump. Unless you are unable to tend to the added preventative maintenance demands, your pool will be better served by staying full throughout winter.
What pool winterizing entails
Of course, even if you do not choose the latter, you must conduct some winterization measures, primarily covering the pool with a quality cover. It is important to choose a cover that is durable enough to withstand harsh winter elements (e.g. freezing temperatures, buildup of snow and ice, gusting winds, etc.); the top options available are mesh, solid safety, and retractable covers, each of which has its own set of advantages.
Complete pool shutdown is not recommended for those using mesh covers, as the material is not as thick compared to the alternatives. When it does come time to drain the pool, you will need to take your time to ensure all water has been flushed from the system, not just what you can see.
Since there is a substantial amount still present in the lines, which is why you should plug each one individually and blow them out with compressed air. Once all remaining traces of water have been forced out, you can proceed to let the pool dry thoroughly before sealing up. This is a great time to inspect and/or replace the pump and motor if need be. The initial winterization process is virtually the same for owners planning to run their pools during winter, albeit with a couple added steps; instead of draining the water, you will need to shock and balance it with the appropriate amount of chlorine and algaecide. Extra chlorine is required to withstand the later shift to warmer temperatures. That in a nutshell is how the winterization process works; do not forget to make periodic pool inspections!