Most in-ground pools will have to be drained and refilled at some point. But cleaning should not be the reason to do it. Pools will need to be drained and refilled every 5-7 years on average, or if there is a major necessary repair. Otherwise, avoid draining your pool if at all possible.
First, if the draining is done at the wrong time or under the wrong conditions, you can actually risk damaging your pool structure and liner. All the water from your pool needs to go somewhere when it's drained, and that usually means the ground.
When should I drain my pool? Pool industry experts recommend you drain your pool and refill it every five to seven years. No two pools are alike, so there is no set number at which you must drain your pool.
If you're wondering why you shouldn't go ahead and drain your pool entirely, it's because the liner of the pool is more vulnerable to damage with no water. The liner will shrink and crack as a result of drying out. Other potential damage includes tears and rips caused by debris during harsh weather in winter.
Why it's never a good idea to drain your pool
In fact, having green pool water is actually a good chance to practice everything that you've learned about pool chemistry and maintaining your pool water.
How long can you leave a pool empty? Well, the minimum amount of time possible in order to minimize the risk of serious damage. Most issues that require a pool drain will take at least a day or two to resolve, but it's recommended to not let it sit empty for any extended period of time.
Draining a pool can take up to 14 hours, depending on the size, so be sure to drain it on a day when you have sufficient free time. You need to be home to check on the pool, the hoses, and the pump frequently. Do not let the pump run dry or it can become damaged.
Never completely drain a fiberglass or in-ground vinyl liner pool; doing so can damage the integrity of the pool surface or liner in the form of bowing or cracking. The best practice is to partially drain these types of pools. Always complete partial drains by 1/3 of the water at a time.
You may naturally assume it's best to completely drain your pool of water for the winter months, because you fear the water will freeze and cause damage. Actually, it's not good to leave your pool empty when the weather gets cold.
An inground pool can pop regardless of type. Concrete, gunite, vinyl, fiberglass—they're all at risk of popping when drained. If it's time to drain your pool, and you want to keep it from popping, consider draining just half the water from the pool, and refilling it.
Why water level is important
Your water should only be drained so it sits just below the skimmer and jets. This helps make sure that no water can get into the pumping system. You may also need to drain a few extra inches of water, depending on the type of pool cover you're using.
Recovering Pool Water
Adjust the pH levels as well as the water hardness. Use pool shock until the dark green water turns blue-grey. Make sure the filter is running throughout until the water becomes clear. Use a clarifier and flocculant to coagulate and drop particles to the bottom of the pool.
The single most important reason to drain your pool is to deal with TDS levels. When TDS levels get too high, they start to interfere with the chemicals at work keeping the water sanitary and clear. More and more chemicals are needed, which can be harsh on the skin and even damage the pool itself.
Most inground fiberglass and concrete pools are built structurally to withstand the weight of the dirt against them when drained. However, if the groundwater is high enough, it can push the entire pool out of the ground. The pool shell acts like a ship and floats up in the groundwater.
The average cost to fill in an inground pool is $4,000 to $16,000 for full demolition or $2,000 to $10,000 to fill in with dirt. An above ground pool removal costs $300 to $800, or $2,500 with a deck. The cost to get rid of a swimming pool depends on the size, depth, material, and accessibility.
Generally, pool water needs to be replaced once every five to seven years. This should be done during mild weather so that your pool surface is not at risk from strong sunlight and heat. Your pool maintenance company can recommend when it is time to drain your pool.
In general, draining this type of pool is the trickiest. Inground pools made of concrete or gunite are susceptible to popping out of the ground if drainage is not done properly. If there has been a surplus of rain recently or your pool is located in a wet area, it is best not to try and drain the pool yourself at all.
A 10,000 gallon pool will take about 14 hours to drain, the maximum rate recommended by the City of Phoenix. It will take twice as long to drain if the pool size is doubled or cut in half.
During normal operation, water flows to the filtering system through two or more main drains at the bottom of the pool and multiple skimmer drains around the top of the pool. The main drains are usually located on the lowest point in the pool, so the entire pool surface slants toward them.
At an average of $0.004 per gallon, city water is the most inexpensive and most popular option. For 15,000 to 30,000 gallons, you'll pay between $60 and $120.
In-Ground Pools
Drain the water down to no more than 6 inches from the bottom of the skimmer if you plan to use a standard floating winter cover. Use your pool filter, switched to the "Drain" setting, to empty the pool water.
If you drain your pool you can cause your vinyl pool liner to shrink and upon refilling, if the liner has lost its elasticity it can cause the liner to rip or tear. The liner can also become hard and brittle. The older the vinyl material is the more likely this is to happen.
If the pool ever needs to be drained to replace the water or to maintain the plaster, it should never be left empty for more than eight to ten days at the most. More than this may cause the plaster to dry out and crack. Keep your pool full for best results.