Is Your Empty Inground Pool a Confined Space

If you ever cleaned or painted an empty Inground Pool, you can easily get the feeling that you are standing in a deep hole 8-10 feet deep and some cases deeper. Add the chemicals involved with Pools like Chlorine or Muriatic Acid then oxygen could be a real problem if you’re not careful. Is your empty Inground Pool a Confined Space?

Yes, empty Inground Pools fit the description of Confined Space, set by OSHA in 29 CFR 1910.146 where the area is configured in a way that could cause a person to become trapped or asphyxiated when volatile chemical cleaners are added to the space.

Working on you’re Empty Inground pools for cleaning, prepping or painting can be dangerous because empty pools can fill with chemical & paint fumes that are heavier than air. This can suddenly happen to a homeowner who doesn’t understand the potential and take some precautions.

OSHA Confined Space Definition

OSHA says that a Confined Space is :

  • Space must be “large enough and so configured that an employee can bodily enter and performed assigned work”
  • Space must “have limited or restricted means for entry or exit” A confined space might be hard to enter and do repair work, or scheduled maintenance. If something goes wrong while you are inside a confined space, escape/rescue may be difficult. Just because a work area has more than one way of escape, does not necessarily mean it is not a confined space.
  • Space must not be “designed for continuous employee occupancy”. This means that space was designed to hold something other than people. Examples include tanks and manholes. 

There are many types of spaces all around us that can be considered Confined Spaces. Some are more dangerous than the next. Confined spaces are usually broken down into two groups: Non-Permit and Permit. Permit-confined spaces are the most hazardous and require you or some qualified person to complete a safety checklist, simply called a permit, before you enter into space.

The in-ground pool has plenty of space to work in and ladders and steps for exit and entrance. While the pool is empty there is easy access to workers inside. The main problem with deep Inground Swimming pools is dealing with chemical fumes found in epoxy and rubber-based pool paint.

Chlorine and Muriatic Acid are that when in gas form heavier than air and can overcome anyone that is at nose and mouth level not to mention over their head.

Muriatic Acid especially is highly volatile in humid weather conditions in or out of the pool. Chlorine can be too. When you are below ground level even on your knees use a cleaner that will turn to gas in warmer humid temperatures they tend to be heavier than the air you breathe at higher levels.

Types of Confined Spaces


If you’re 10 feet deep in an Inground pool and scrubbing the walls of the pool with Muriatic Acid to clean and prep the inside area, you’re most likely already breathing it. Over time even if you are careful it could catch up to you.

OSHA defines a PRCS as any confined space that meets one or more of the following:
“Contains or has a potential to contain a hazardous atmosphere” (the aforementioned bad air)
“Contains a material that has the potential for engulfing an entrant”
“Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section”
Or “Contains any other recognized serious safety or health hazard”.

An In-ground empty swimming pool has the potential for a hazardous atmosphere especially when chemicals are being used to edge, strip or paint the walls and floors of your pool. Chemicals can react with water vapor to create a gas cloud that is heavier than air and sinks down pushing oxygen up higher in space, where the person that is below ground level can be asphyxiated. According to OSHA Asphyxiation is the leading cause of death in confined spaces. 

I have been in some nasty places that require a permit from OSHA in my line of work with Wastewater. Atmospheric testing was a standard for all entries in manholes or tanks where gases that could collect and kill people sometimes did. These types of Confined Spaces were called Permit Required or (PRCS) because testing would have to be documented each time there was access to the site. They were considered dangerous

Each entry into a questionable place was certified and documented with at least one extra safety person on-site and an initial gas reading for lack of Oxygen which is 20.9 ppm for normal concentration. If the first reading was not good or unsure the Confined Space was blown out with an Air Blower or forced air ventilation. A slight drop in Oxygen, a reading of 19.5 would be cause for alarm in any given situation. 

The same gases wouldn’t be found in an empty Inground pool but lack of oxygen would surely be a concern. A pool with no top and a nice blue sky can be deceiving if the walls are high enough to trap toxic gases or fumes inside you.

Low oxygen levels (19.5 percent or less) can cause symptoms such as rapid breathing, rapid heart rate, clumsiness, emotional upset, and fatigue. As less oxygen becomes available, nausea and vomiting, collapse, convulsions, coma, and death can occur.

Unconsciousness or death could result within minutes following exposure to a simple asphyxiant. Asphyxiants include argon, nitrogen, or carbon monoxide. You could be working and not know that these minimal changes are happening resulting in a bad situation.

Reasons to Drain a swimming pool


There are plenty of reasons to empty a concrete Inground Swimming Pool in fact every 3-5 years most owners like to paint their pools which can take a lot of prep work and could keep it empty for a week or more fixing and resurfacing the inside until it’s ready to paint.

The problem most people don’t understand is that an Inground Pool is considered a Confined Space and could be very dangerous to work in. In my field of work, I was trained in Confined Space Entry and Rescue and there were places that I have been in places where in order to enter Oxygen levels needed to be tested.

I and fellow workers needed to be tied off and safety forms were filled out proving that the areas were safe. My Inground Pool was just as dangerous, if not more because most people that are in a concrete empty pool to paint it are using Epoxy paints that contain fumes that will hurt you or worse.

Please remember this,  as I have seen problematic situations in smaller spaces that were being taken for granted.  Never Work Alone! 

Always keep a running water hose in the immediate area of the pool and where you are working. Freshwater can be a lifesaver especially when you work with acids or other strong cleaners. Remove any hoses or tools inside the pool. If you need to get out in a hurry, you don’t want to trip and fall back into the pool.

Remove any other chemicals like Chlorine and especially Bleach that you may have been using before. Bleach will not mix with Muriatic Acid. It will create a toxic gas.  So when you’re clean with Muriatic everything comes out. Try and pump as much water as you can because you will be adding more water when you start to rinse after cleaning.

Etching cleaning and painting all should be done on dry days for a few reasons. Some chemicals like Chlorine Muriatic Acid or Hydrochloric Acid react with a minimal amount of water including humidity which is water in the air.

Always work in pairs. One person has access to a cell phone and the other end of a rope

Keep a Leaf Blower up top out on top of the pool. If there is a problem, your partner can blow and clear fumes from up top. In a pinch, a Leaf Blower will dissipate a chemical cloud and pump some fresh air into the pool. In lieu of a portable Ventilator.

It’s not the best solution but it could be a lifesaver when there is no other recourse. There won’t be time for fire or rescue personnel to come and pull a victim out of the pool who is overcome by fumes. A partner can never enter the same space as the victim if it’s determined that the victim is overcome by fumes. It’s not an option. First responders are taught this.

Keep a length of rope for an emergency to tie a worker in the pool and one up top outside off to be pulled out of the pool instead of trying to go in and retrieve them. You can easily drag a person up the slope that is found in most deep Inground pools.

Never Go Into An Confined Space To Try And Rescue Someone!

Whatever happened inside the pool will most likely happen to you. You are better off using the leaf blower to push fresh air down into the deep part of the pool where the victim is unconscious. Or using the hose to flood the area. But don’t go in. Remember what OSHA says Asphyxiation is the leading cause of death in confined spaces.

Using Muriatic Acid To Etch the Inside of the Pool.


Muriatic Acid is great for cleaning and etching concrete and bricks around and inside the pool.  It will strip the worst algae-stained concrete pool. Muriatic Acid comes in different concentrations.

Muriatic acid isn’t pure hydrochloric acid, nor is there a standard concentration. It’s important to check the product label to know the concentration. Some industrial suppliers offer muriatic acid which is 31.5 percent HCl some are 29-31.5 and 14.5 % by mass (20 Baumé).

Use a more stable less concentrated form of Muriatic Acid that is safer to use.  The acid is very volatile and must be used with safety precautions. It’s highly corrosive and reactive.

  • Use chemical-resistant container eye protection and gloves. A long handle (save your back) Hard Bristle Scrub Brush.
  • Reaction with oxidizers, such as chlorine bleach (NaClO) will produce toxic chlorine gas.  So if you are using chlorine bleach get rid of it.
  • If you need to neutralize it for any reason like a spill while you cleaning use Sodium Bicarbonate and fresh water.
  • Don’t be sloppy. Mix one batch of Muriatic Acid at a time  -(always pour Acid into water) never water into acid-Use a reliable chemical-resistant container.
  • Mix the Batch on top-out of the pool area and in the fresh air so you don’t spill it in the pool space where you are working.
  • Work on the deepest area, floors, and walls first slowly working your way out of the pool.
  • Apply the Acid or Bleach to the higher ends of walls from up top and rinse with the garden hose from up top. Use plenty of fresh water.

Life is not always safe and there is no guarantee on anything but common sense, as my Grandmother used to say can go a long way. An empty Inground pool is a big hole in your yard. There are plenty of ways to hurt yourself, falling being the obvious one.

From good practical experience, I can tell you that using cleaning chemicals even household cleaners poses an unseen danger that could come out of nowhere. Be careful. Getting your pool ready should be fun!


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JimGalloway Author/Editor




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