The Anatomy of a Swimming Pool

What is a swimming pool? When you boil it all down, a swimming pool is just a giant structure that holds a large amount of water. However, each swimming pool is different in its own special way.


Some pools are above ground and some are in-ground. They can have different surfaces like vinyl, tile, plaster or fiberglass. No matter which type of pool you have, they all do the same thing: provide entertainment and a means of cooling off.

City Water Vs. Well Water

Depending on where you live and what type of water system you have, your water make-up can be vastly different. City water is, of course, provided by your city or town. It’s plumbed directly to your house from a main water supply.

Well water comes from a well in the ground that resides on your property. The big difference between well and city water is that the chemical make-up of city water is controlled by a professional facility, and well water is controlled by you.

Well water tends to have more minerals, including copper and iron, which can be bad for your swimming pool. So, with well water, there are a few extra steps in chemistry, but it’s nothing to worry about.

Common Pool Water Contaminants

Since most swimming pools are located outside, and we all live on planet earth, we experience a lot of the same water contaminants in our pools. Some common ones include:

  • Leaves from trees
  • Insects
  • Human sweat, make-up, lotions, oils, etc.
  • Micro-organisms such as bacteria and algae
  • Natural elements such as calcium, various metals, and nitrogen

An In-Ground Pool Anatomy

Here is a drawing of a basic in-ground pool set up. This illustrates the places where water comes in and out of your pool. Water is sucked in through the skimmer(s) and the main drain(s), pumped through your filter, and then back into your pool through the return lines.


Note: This is not how EVERY in-ground pool is set up, but the logic works the same way. Every pool has a skimmer to suck in the water into and through the filter, and every pool has a return line to push the water back into the pool.

The Suction-Side Of Your Pool


pool-skimmer.jpgThese are buckets, built into the concrete, that house a skimmer basket (hence the term, skimmer). Skimmers are what suck the water out of the pool and through your filter system. They should have a small plastic basket inside to catch any large debris including leaves, sticks, and bugs before it enters your pump (which also has a basket).

Main Drain

main-drainThis is another place where water is sucked in and pushed through your filter. Main drains are usually located at the bottom of the deep end of the pool. While the skimmers take care of pulling water off the top of the pool, main drains are great for pulling water off the bottom. That way, you are pulling water from all areas of the swimming pool.

Note: Older in-ground swimming pools probably won’t have two main drains. The reason why newer pools have two is for safety. When you have two, it splits the suction in case something or someone blocks one of the drains.

The Pressure-Side Of Your Pool

Return Jets

This is the jet that pushes the water back into your swimming pool after it’s been filtered. The jets also help to push or circulate the water around, allowing the skimmers a better chance to pick up more debris.

Tip: If you have two or more return jets in your pool, angle some of them down towards the floor and in one direction, either left or right. You want to create a circular motion while helping to kick debris off the bottom with the jets angling down.

Note: If you have jets in your steps, these are also return lines.

Your Filtration System

Your filter system should be made up of two parts, the pump and the filter. Often, owners will refer to these as one unit, but they are completely different. Your pump is what moves the water and the filter is what…well…filters it or cleans the water.


The Pump

This is the unit that draws in the water from the pool, pushes it through the filter and back into your pool. It consists of two parts. The pump, which technically is the bucket with a lid and a basket inside. There is also an impeller that spins super fast. That’s what sucks the water in and out.

The other part is the motor. The motor is the heavy long tube shape piece behind the bucket with the lid. Its job is to spin that impeller and spin it fast. Pumps come in all shapes, sizes and speeds. The speed is what’s really important. It’s measured in Horsepower and it ranges from ¾ horsepower to 3 horsepower, on average.

Smaller pools don’t require as much horsepower as a larger pool. So, the bigger the pool, the bigger the pump and motor.

The Filter

Once the pump has sucked the water in, it immediately pushes out into your filter. You filter cleans out the water of fine debris and then it moves back into your swimming pool. There are three types of filters to clean your swimming pool, sand, D.E.(diatomaceous earth) and cartridge. They all filter out tiny particles from your pool water.

Extra Equipment

What we just talked about are the main ingredients to a functioning swimming pool, but you can always add more the party.

A Heater

swimming-pool-heaterI think this goes without saying, but yes, a heater heats up your pool water. It’s a nice feature to have on your swimming pool and you can get it on both above ground and in-ground pools. There are a few types of pool heaters including natural gas, propane, electric and solar. Although, it’s not a necessary piece of equipment when it comes to circulation and cleaning your pool, it’s just awful nice to have.

A Chemical Feeder

chemical-feeder-swimming-pool.jpgThis handy little piece of equipment makes adding pool sanitizer to your pool easy. Just fill it full of the correct sanitizer (i.e. chlorine, bromine or a mineral cartridge) and let her rip. This is the last piece of equipment in your filtration line. The order of equipment is as follows:

  • Pump
  • Filter
  • Heater
  • Chemical Feeder

You don’t want to add the chemical feeder before a heater because the water coming out of the feeder has got a bunch of chemicals in it and will take a toll of the inside of a heater over time.

In Conclusion

This is the basic anatomy of a swimming pool. Everything we talked about should give you a general idea on how a pool operates. To sum it up, the water in your pool is sucked into the filter by the pump from the skimmers. The water then runs through your filter (sand, D.E. or cartridge) and is pushed back into your swimming pool via the return jets.

Hopefully, this very basic understanding should lay the ground work for proper pool care so that you and your family and friends can enjoy a crystal clear and clean pool all season long.

My 3 Cs of pool care include: cleaning, circulation and chemicals. I suggest you read these posts to understand how to keep your pool clean and healthy all season long:



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