When and Why You Might Need to Empty Your Pool
Owning a swimming pool brings joy, relaxation, and recreation to your home, but there are times when the pool needs to be partially or completely emptied. Understanding when and how to properly drain a swimming pool is essential knowledge for every pool owner, as improper draining can lead to serious structural damage, environmental problems, and costly repairs. While the idea of emptying a pool might seem straightforward, the process involves careful planning, the right equipment, and awareness of local regulations that govern where and how pool water can be discharged.
There are several common reasons why a pool owner might need to drain their pool. Chemical imbalances that cannot be corrected through normal treatment, such as excessively high levels of cyanuric acid (stabilizer), total dissolved solids (TDS), or calcium hardness, may require draining and refilling with fresh water. Major repairs to the pool's interior surface, such as replastering, retiling, or fixing structural cracks, typically require the pool to be emptied. Painting or refinishing the pool deck or coping may also necessitate lowering the water level significantly.
Algae infestations that are resistant to chemical treatment, contamination of the pool water by substances that cannot be safely removed through filtration or chemical treatment, and winterization in regions with severe freezing conditions are additional reasons for draining. However, it is important to note that a pool should never be drained unnecessarily, as the process carries inherent risks to the pool structure and should only be undertaken when there is a clear and compelling reason to do so.
Understanding the Risks of Draining a Pool
Before you begin the draining process, it is crucial to understand the risks involved. The most significant risk is structural damage to the pool itself. In-ground pools, particularly those made of concrete, gunite, or fiberglass, are designed to hold water, and the weight of the water actually helps hold the pool in place against the pressure of the surrounding soil and any groundwater that may be present.
When an in-ground pool is emptied, the hydrostatic pressure from groundwater beneath and around the pool can push upward against the pool shell, potentially causing it to crack, shift, or even pop out of the ground entirely. This phenomenon, known as "pool pop," is particularly common in areas with high water tables or after heavy rainfall and can result in catastrophic damage that is extremely expensive to repair.
Fiberglass pools are especially vulnerable to damage when emptied, as the shell can flex, crack, or develop bulges when not supported by the weight of water. Vinyl-lined pools can also be damaged during draining, as the liner may shrink, wrinkle, or pull away from the walls when exposed to air and sunlight. For these reasons, many pool professionals recommend that pool owners hire experienced pool service companies to handle draining rather than attempting it as a DIY project.
Checking Local Regulations
Before draining your pool, you must check local regulations regarding the discharge of pool water. Pool water contains chemicals such as chlorine, bromine, algaecides, and other treatment products that can be harmful to plants, animals, and aquatic ecosystems if discharged improperly. Many municipalities have specific ordinances governing where and how pool water can be disposed of.
In most areas, pool water must be dechlorinated before it can be discharged into the storm sewer system, which typically drains directly to natural waterways without treatment. Chlorine levels should be reduced to below 0.1 parts per million before discharge, which can be achieved by stopping chemical treatment and allowing the chlorine to dissipate naturally over several days, or by using a chemical dechlorinator.
Some jurisdictions require that pool water be discharged into the sanitary sewer system rather than the storm sewer system. The sanitary sewer carries wastewater to a treatment plant where it is processed before being released into the environment. Discharging pool water into the sanitary sewer may require a permit or notification to the local water authority. Discharging pool water directly onto neighboring properties, into streams, lakes, or wetlands, or into areas where it could cause erosion or flooding is generally prohibited and can result in fines.
Methods for Draining a Swimming Pool
There are several methods for draining a swimming pool, and the best choice depends on the size of the pool, the speed at which you need to drain it, the equipment available, and local regulations. The two most common methods are using a submersible pump and using the pool's built-in drain system.
A submersible pump is the most common and effective method for draining a swimming pool. These electric pumps are placed directly in the pool water and can move large volumes of water quickly and efficiently. Submersible pumps are available for purchase at home improvement stores or can be rented from equipment rental companies. When selecting a pump, consider the size of your pool and the desired drainage time to choose a pump with appropriate capacity.
To use a submersible pump, place the pump in the deepest part of the pool and connect a discharge hose that directs the water to an appropriate disposal point, such as a sanitary sewer cleanout, a storm drain (after dechlorination), or an area of your property where the water can be absorbed without causing erosion or flooding. Plug the pump into a ground fault circuit interrupter (GFCI) protected outlet and turn it on. Monitor the draining process regularly to ensure the pump is functioning properly and the discharge area is handling the water flow without problems.
Using the Pool's Main Drain
Some pools are equipped with a main drain that can be used in conjunction with the pool's filtration pump to lower the water level. This method involves switching the pool pump to the "waste" or "drain" setting on the multiport valve (if equipped), which directs water from the pool through the pump and out through the waste line rather than back into the pool through the return jets.
This method is generally slower than using a dedicated submersible pump, but it has the advantage of using equipment that is already installed and connected. It is particularly useful for partial draining, such as lowering the water level by a foot or two to reduce chemical concentrations or to accommodate heavy rain. For complete draining, a submersible pump is usually more practical because the pool's built-in pump will lose prime (the ability to draw water) as the water level drops below the skimmer intake.
Step-by-Step Pool Draining Process
The process of draining a swimming pool should follow a systematic approach to minimize risks and ensure the job is done correctly. Begin by checking the weather forecast and choosing a period of dry weather for the draining project. Draining during or immediately before heavy rain increases the risk of hydrostatic pressure damage, as rainwater saturates the soil around the pool and raises the water table.
Next, stop adding chemicals to the pool several days before draining and test the water to ensure chlorine levels have dropped to safe discharge levels. Remove any debris, equipment, and accessories from the pool that could interfere with the draining process. Set up your submersible pump in the deepest part of the pool and route the discharge hose to the appropriate disposal point.
Begin pumping and monitor the process regularly. As the water level drops, check for any signs of structural stress such as cracking, shifting, or deformation of the pool walls or floor. If you notice any concerning signs, stop draining immediately and consult a pool professional. In hot weather, avoid leaving a plaster or concrete pool empty for extended periods, as the sun can cause the surface to dry out, crack, and deteriorate.
Once the pool is empty, work quickly to complete whatever maintenance or repairs necessitated the draining, and begin refilling the pool as soon as possible. As the pool refills, monitor for leaks and begin rebalancing the water chemistry once the pool is full. Test and adjust the pH, alkalinity, calcium hardness, and sanitizer levels to bring the water back into the proper range for safe and comfortable swimming.
Professional Help vs. DIY
While draining a pool is technically a task that a capable homeowner can perform, there are compelling reasons to consider hiring a professional pool service company for this job. Professionals have experience assessing the risks specific to your pool type and location, they have commercial-grade equipment that can drain the pool more quickly and safely, and they understand local regulations regarding water discharge.
Professional pool companies also carry insurance that covers damage that might occur during the draining process, providing financial protection that a DIY approach does not offer. If your pool is fiberglass, has a vinyl liner, or is located in an area with a high water table, professional assistance is strongly recommended due to the higher risk of structural damage associated with these conditions.
Whether you choose to drain your pool yourself or hire a professional, the most important thing is to approach the process with respect for the risks involved and a commitment to doing the job safely and correctly. A properly drained and refilled pool will serve you well for many years, while a carelessly drained pool can result in damage that is costly, time-consuming, and frustrating to repair.
