How Often Should You Drain and Refill Your Pool?

Mark Larm Aug 10, 2023
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When should you drain your swimming pool? How often to drain pool?

How Often Should a Swimming Pool Owner Drain and Refill Their Pool?


Maintaining a swimming pool is a rewarding endeavor that offers countless hours of relaxation and enjoyment. However, proper pool maintenance is essential to ensure the safety and comfort of swimmers while preserving the longevity of your pool equipment. One critical aspect of pool maintenance is the regular assessment of when to drain and refill the pool. In this blog, we'll explore the factors that influence the frequency of pool water changes, signs indicating the need for a change, guidelines for how often to consider draining and refilling, and the steps involved in the process. 

Factors Influencing Pool Water Change Frequency

Water Quality: Maintaining optimal water quality is paramount for a safe and enjoyable swimming experience. Regular water testing helps monitor key factors like pH levels, chlorine concentration, alkalinity, and calcium hardness. These parameters influence the effectiveness of your pool's disinfection and can impact the clarity and comfort of the water. Unbalanced water chemistry can lead to skin and eye irritation, while excessive hardness can cause scaling on pool surfaces and equipment.

Pool Usage: The frequency and manner in which your pool is used significantly affect its water quality. Pools used more frequently and by a larger number of swimmers are more prone to contaminants. Swimmers introduce sweat, oils, lotions, and “other organic matter” into the water. Proper hygiene practices, such as showering before swimming, can help reduce the load of contaminants, thus extending the time between necessary water changes.

Environmental Conditions: Your pool's environment also plays a crucial role in determining when to drain and refill. External factors like dust, debris, and pollutants can find their way into the water, impacting its clarity and quality. Weather conditions, such as heavy rain or extreme heat, can affect the pool's water balance. Rainwater can alter pH levels and dilute chlorine, while hot temperatures can accelerate chlorine degradation.

Signs Indicating the Need for Water Change

Chemical Imbalance: An imbalanced pool chemistry can manifest in various ways. If you notice that your chlorine levels are consistently ineffective at maintaining water clarity and disinfection, it might be time for a water change. Cloudy water and unpleasant odors can also indicate a chemical imbalance that routine maintenance struggles to rectify.

Algae Growth: Algae growth is a common issue in poorly maintained pools. If you're experiencing persistent algae blooms despite regular treatments, it could be a sign that your pool water has reached a point where it needs to be refreshed.  

Stains and Scaling: Mineral deposits and scaling on pool surfaces can occur when water hardness levels are too high. If you're struggling with persistent stains or scaling despite your best efforts to balance the water chemistry, a water change might be the solution.

Frequency of Draining and Refilling

General Guidelines: The good news is that you can test your water and determine if it needs to be changed. TDS (Total Dissolved Solids) should range from 500-3,000 and can be tested at a local pool store or by purchasing specific test strips. While the specific timeline for draining and refilling a pool can vary based on individual circumstances, a general guideline is to consider doing so every 7 to 10 years. This range takes into account the factors mentioned earlier. Regular testing and diligent maintenance practices can help extend the time between full water changes. I had one client that needed to have his pool drained in only 3 years. Surprise, his son was washing the dogs in the hot tube. 

Regular Maintenance vs. Full Water Change: It's important to note that routine maintenance, including regular testing, skimming, vacuuming, and backwashing, should be a continuous effort. These practices help maintain water quality between major water changes. A full water change, on the other hand, involves draining the entire pool and refilling it with fresh water.


I like to tell my clients it’s like having fresh bath water. If you didn’t have the pool built then you're swimming in someone else's old bath water. Yes, it looks clean but is it? You won’t even take a bath in the same bathwater that your kids were in but you’ll jump into a swimming pool of only God knows what from the previous owners. 

The truth is that it’s usually the fear of how much money is it going to take. Here in California it’s like pulling teeth to get clients to drain their pool but back east and in the Midwest they seem to have no trouble making the decision to change the water. 

What is the real cost? It can get to the point that you're spending more money on chemicals to fight algae than it would cost to actually refill your pool with fresh water. I service pools that truly take twice as much chemicals to maintain as it would with fresh water, their kids are swimming in that.

The secondary cost is when the water gets so out of balance. If your pool is having calcium build up all over the tile and spa overflows there is a cost associated with having that removed. Having a Bead Blaster out can cost from $7-$10 a foot. You can add calcium hardness removers to the pool at about $100 a gallon but if you are already having buildup on fixtures like your pool light then it's going to cost as much as refilling your pool with fresh water and starting over fresh. 

The hidden cost, some people just want to be eco friendly and don’t want to see all that water go down the drain. Great news for you, you can let the chlorine dissipate and get a sump pump in the pool and irrigate your trees and yard. Ask your neighbors if you can borrow their garden hose and see if they will let you water their trees also. The truth is there is a growing business opportunity for the southern states to filter the water in the pool. Yes, you heard me correctly, a big truck with an RO (Reverse Osmosis) system on it comes out to your house and filters the water back down to 0 TDS (Total Dissolved Solids) making it completely eco friendly. FYI, the cost is usually the same as a drain and refill. 

Steps to Take Before Draining and Refilling

Testing and Analysis: Before you embark on the process of draining and refilling, conduct a thorough water analysis. Test the pool water for TDS, pH, chlorine, alkalinity, and calcium hardness levels. This analysis will guide you in making the necessary adjustments to see if draining is even necessary.

Equipment Inspection: Take this opportunity to inspect your pool equipment. Check for any issues with the filtration system, pumps, and pipes. Addressing any maintenance needs before draining can save you from potential complications during the refilling process.

Process of Draining and Refilling

Draining the Pool: (if you have an inground vinyl pool never drain it, it will collapse. Let water out on one side while adding fresh water to the opposite end.) To begin the draining process, you can use a submersible pump or your pool's built-in drain system. If using a submersible pump, place it in the deepest part of the pool and allow it to remove the water gradually. Ensure that the drained water is disposed of properly according to local regulations.

Refilling the Pool: Connect a garden hose to a clean water source and begin refilling the pool. I do recommend having your water from the house tested just to be prepared for treatment when your pool is full. I also recommend getting a couple in-line filters that connect to your garden hose to ensure you start off with the cleanest water possible especially if you have high calcium hardness levels. Keep an eye on the water's progress and ensure that it remains clean and clear and you don’t over fill it, why waste any more water than necessary. 

If you’re on well water be cautious not to overload your water supply and possibly burn out your pump. Unlike fresh plaster or a re plaster that needs to have one continuous fill so the plaster doesn't get any lines or color ganges in it an older pool can take the beating. 

Test your well water, sometimes it is just better to have a truck load of good quality water delivered for your initial fill, then use a pre filter to top off the pool when necessary. 

Post-Refill Steps and Maintenance

Chemical Balancing: Once the pool is filled, retest the water and adjust the chemical balance as needed, don’t forget to get the conditioner in there right away. This step is crucial to providing a clean and safe swimming environment.

Filtration and Circulation: Ensure that your pool's filtration and circulation systems are operating optimally. Proper water movement and filtration are key to maintaining water quality and clarity.

Regular Maintenance: Remember that maintaining a clean and balanced pool is an ongoing effort. Continue with regular maintenance practices such as skimming the surface, cleaning the filter, and vacuuming the pool floor.


In conclusion, the question of how often to drain and refill your swimming pool depends on a variety of factors, including water quality, pool usage, and environmental conditions. Regular testing, diligent maintenance, and proactive steps to address signs of imbalance can help extend the time between full water changes. By following the guidelines outlined in this blog, you can ensure that your pool remains a safe, inviting oasis for swimmers to enjoy for years to come. Remember, a well-maintained pool not only provides leisure but also contributes to the overall health and well-being of those who use it.

Don’t forget to cruise around the website and look for any of the products mentioned here and visit me on YouTube @happypools