Important Factors That Affect When You Can Swim in a Newly Filled Pool

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A pool that’s been freshly filled with water can be truly tempting to hop right into, especially in the hot summer months.  

In many cases, the pool may have been filled over the course of a day or more with your garden hose supplied by either city-water or well-water.  In other instances, pretreated water may have been trucked in with a tanker to provide quick filling of the pool.

While the water may be sparkling blue, you may wonder “How soon can you swim in a newly filled pool?”  

Most of us drink the water and take showers from the same source that is used to fill the pool.  This makes it pretty clear that there’s not much concern in taking that initial dip into a newly filled pool.

However, as we all know, it’s important that chemicals are added pretty quickly in order to keep the water clear and safe for swimmers.  Once the chemicals have been added, that’s when the timeline can vary as to when you can swim. 

Aside from the types of chemicals added, the size of the pool, and water temperature are other important considerations that could affect the timetable for getting into the water.

In this post we’ll look at the factors that can affect just how soon you can swim in a newly filled pool.  Let’s dive right in!

Factors Before Swimming in Freshly Filled Pool

Water chemistry, the size of the pool, and temperature are important considerations that could affect the timetable for getting into the water.

Water Chemistry

The most important factor in determining when you should swim in a newly filled pool is the state of the water balance.  Chemicals are required in order to keep the pool safe and clean for swimmers, but they can also be harmful if not used properly. 

While it’s OK to take that initial dip into the pool immediately after filling, once you’ve added chemicals you’ll need to allow them time to disperse before jumping back in.  The amount of time you need to wait will depend on what was added to the water.

The most conservative approach is to allow time for at least one turnover of water, which is often around 10 hours.  For this reason, chemical addition is often recommended at night so that the pool is ready to swim the following day.

Various chemicals are used to achieve the necessary levels of sanitizer, pH, alkalinity, and stabilizer (cyanuric acid).  Other chemicals, such as algaecides and metal sequestrants may also be used to help maintain the water.

In general, once the sanitizer and pH have been balanced to appropriate levels, the newly filled pool is ready to swim.  

Several common types of sanitizers used in pools are chlorine, bromine and saltwater chlorine generators (SWCG).  

Traditional Chlorine

Traditional chlorine is the most common sanitizer used in pools.  It comes in various forms like tablets, granular, and liquid.

Regardless of which chlorine you are using, you’ll want to ensure the free chlorine (FC) measurement is within the safe level of 2 to 5 ppm.  In general, readings above 6 ppm are considered unsafe and could lead to irritation of skin and eyes. 

Once you’ve added chlorine to a freshly filled pool, it’s advised that you use a test kit to verify you are within the safe range.  

If using chlorine tablets to treat the pool, it may take 24 to 48 hours to elevate the FC to the appropriate level.  

If initially treating the pool with a chlorine shock, the FC may increase to unsafe levels very quickly.  However, since most chlorine shock is unstabilized, it will break down quickly.  You should wait at least 12 hours or until FC has fallen back to 5 ppm.  


Bromine is commonly used as an alternative to chlorine for sanitizing the pool.  It most commonly comes in tablet form, but may also be found as liquid or granular.

While bromine is often considered gentler on swimmers than chlorine, it is still important to keep it within a safe range.  A safe range for bromine is often 3 to 5 ppm.  

Similar to chlorine tablets, bromine tablets may take 24 to 48 hours to elevate the bromine level to the appropriate range.  If bromine levels exceed 6 ppm, it best to wait for them to fall back down before entering the water –sunlight and temperature are factors that could affect how quickly this occurs.

Saltwater Chlorine Generators (SWCG)

Saltwater chlorine generators are a great alternative to standard methods of sanitizing the pool.  The SWCG converts saltwater into chlorine through electrolysis. 

In order to prepare a newly filled pool, you’ll need to add a hefty amount of salt in order to achieve the baseline salinity of about 3200 ppm.  This generally requires about 250 pounds of salt per 10,000 gallons of water.  

After adding the salt, it’s best to wait until you can see the bottom of the pool before jumping in for safety reasons.  Sometimes this can take upwards of an hour depending on how quickly the salt dissolves into the water.  

Other Common Chemical Additions

When adding any type of chemicals to your pool, it’s important to read the manufacturer’s label.  Here are some other types of common chemicals with rough timelines for swim-ability:

  • Muriatic Acid: This is used to lower the pH in the pool.  You will need to wait at least 30 minutes before swimming after addition of muriatic acid in order to ensure it has dispersed.
  • Baking Soda & Borax: These are used to increase total alkalinity and pH.  Swimming can occur immediately after addition.
  • Flocculent: This will help provide clarification of the pool water by clumping together with small particles.  It’s best to wait to swim until the clumps have fallen to the bottom and have been vacuumed out.
  • Algaecide: This will help prevent algae growth in the pool.  Most algaecide allows swimming immediately after addition.
  • Calcium chloride – This will help soften water that has high hardness levels.  It’s recommended that you wait at least 2 hours before swimming.  

Size of the Pool

The size of your pool may also affect the amount of time before it’s safe to swim in a newly filled pool.  Larger pools may require more time for the water to circulate and the chemicals to disperse evenly than for a small pool.


If your pool has been filled through a hose, either through city or well water, it’s more than likely that it will be very chilly.  Water lines that are underground will often supply water that is around 55°F.

It’s generally recommended that pool temperature is 70°F or above for safety reasons.  Water that is cooler than 70°F can cause increased heart rate and blood pressure.

If it’s warm and sunny outside, this will help heat your pool gradually.  However, it could take several days to reach a comfortable temperature.

If you have a pool heater, this will be the best means to boost the temperature quickly.  Even a wood burning heater may be used to heat the pool quickly and cheap, if you have a plethora of wood available.

Plastered Pool

If you’ve just re-filled the pool after plastering it, you may need to wait several days before jumping in.  Once the pool has been filled, the plaster will continue curing underwater and could be susceptible to damage if swimmers bump the walls.

While there’s no full agreement with industry experts on the exact timetable, many recommend waiting at least 5 days.  Others indicate that when no more plaster dust is visible during brushing, then it’s ready to swim.

If an acid wash was performed prior to filling the pool, then you’ll also want to wait until the pH has stabilized –this could be upwards of 10 days.

Risks of Swimming in a Newly Filled Pool

While there’s plenty of excitement of diving into a freshly filled pool, there are some potential risks to be aware of.  Many of these signify the importance of getting the pool balanced so that it’s safe for swimmers:

1 – Chemical imbalances: When a pool is first filled, the chemical levels can be unstable and unbalanced, which can cause skin and eye irritation.

2 – High chlorine levels: In an effort to sanitize the pool, some people may over-chlorinate the water, which can cause respiratory problems, skin irritation, and eye irritation.

3 – Algae growth: Algae can grow quickly in newly filled pools, especially if the pH levels are not properly balanced. Algae can cause health issues, and it can also make the pool slippery and unsafe.

4 – Bacterial growth: If the pool is not properly maintained, it can become a breeding ground for harmful bacteria, which can cause infections and illnesses.

5 – Drowning: It’s important to supervise children and weak swimmers when they are in or around a pool, as they can quickly become tired and may not be able to swim to safety.

To minimize these risks, it’s important to properly maintain the chemical levels. Supervision is also necessary especially when swimming in unfamiliar or newly filled pools.

Final Takeaway

Swimming in a newly filled pool is a fun and exciting experience for everyone.

While it’s OK to dip in immediately after filling, you’ll want to prioritize getting the pool balanced to the right sanitizer, pH, and alkalinity levels as soon as possible.  This process can often take a day or more of various chemical additions before the water is considered safe –ultimately, measuring the water with a pool test kit is the best way to ensure the pool is balanced.

Even beyond water chemistry, the temperature of the water is also important.  Swimming in cold water can put stress on the body leading to increased potential of health complications.  Ensure you allow ample time for the pool temperature to increase to a safe level.

Happy Swimming!

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