Answer:

Not necessarily. Many people never completely drain and refill their pool because they are lowering the level significantly every winter and then refilling with fresh water in the spring. This dilutes the level of total dissolved solids (TDS), cyanuric acid and other chemicals that would otherwise require the pool to be drained and refilled. You can also make several partial drains over the course of a couple of years that would help to do the same thing as a complete drain. If you do not close the pool and/or make regular partial drain and refills, you may want to consider a complete drain in order to lower the levels mentioned above. Old water that is not diluted with fresh water can cause problems keeping the water balanced, make the water look dull and dirty and can potentially cause damage in the form of build up and scale. Note: pools with a vinyl liner that require complete drain and refill should probably be handled by a professional. Vinyl liners are kept in position by the water and when there is none, the liner can shift or shrink and then tear or wrinkle when the water is added back in.