Can You Use Black Garbage Bags to Heat the Pool?

I always thought that I wasn’t a pool person until I realized that I was just really sensitive to the cold. Temperature plays a major role in my ability to enjoy lounging or swimming in the pool, and I tend to stay on the warm side of things. Even a change of a few degrees can be the difference between too chilly for comfort and just right.

Unfortunately, heating up a pool can cost hundreds of dollars a month – money that I didn’t want to spend. So I looked for various ways to heat up my pool for cheap, and out of the many methods that I tried, one that stood out to me was using back garbage bags to heat the pool.

Are black trash bags really enough to heat your pool? In my experience, it’s not an effective solution and causes more problems than it solves. It’s not as simple as just chucking black trash bags on the surface of your pool and then suddenly your pool is warm. You have to worry about cleanup and it doesn’t even trap heat as efficiently as a solar pool cover.

In this article, I’ll go over this supposed black garbage bag solution – what people are saying you should do, and why it’s not as great as they’re saying it is. I also provide a much better solution to heat your pool for cheap instead.

How do you heat your pool with black trash bags?

The rationale is that black plastics absorb the most sunlight out of any other color. Therefore, leaving black garbage bags floating along the surface of your pool will allow them to heat up and transfer that energy to your pool water, warming it up. It may also decrease evaporation slightly.

The recommended way to do this is to fold a pool noodle into a circle and then wrap the trash bag over it or fold a bag over a hula hoop and secure them with waterproof tape to create your own DIY solar ring. Then you try to cover as much of the pool’s surface with the black trash bags as you can.

Some people claim that, after using the garbage bag trick, their pool water was warm after only two hours. I think your mileage may vary because the results can depend on various factors such as the size of the pool and how warm the climate is.

The downsides of using black garbage bags for pool heating

In my experience, I did not notice any difference in water temperature and, even worse, I noticed tiny plastic bits getting into the pump’s basket.

Turns out the garbage bags were deteriorating due to prolonged exposure to chlorine. This is an issue because the small debris can overheat the motor by getting tangled in the impeller.

Not to mention, cleaning up can be a pain. So unless you want to create a huge mess that you have to clean up, you need to be very careful about the garbage bags that you use.

Using black garbage bags to heat your pool the “right” way

As you can probably tell by now, I am recommending you look for a different pool heating solution. This solution is more hassle than it’s worth and provides mediocre results.

If you’re dead set on using trash bags are your means of heating, then heed the following advice:

  • Use the thickest garbage bags you can get. I recommend garbage bags that are at least 3 mil thick. Any thinner than that, and the plastic is less durable and more likely to fall apart. Once there are thousands of bits of plastic floating around in the pool that you have to clean up, you’ll wish you had followed this step.
  • Rinse the chlorine off of the garbage bags. Every couple of days, give your trash bags a rinse. This will prolong their life because otherwise chlorine will deteriorate the plastic. You even need to do this with pool-rated solar rings and solar covers, so you definitely should do the same with the garbage bags.
  • Through the bags away when they get worn down. Look, I know you’re trying to save money, but once the trash bags get porous and thin, it’s time to replace them. Otherwise, the bag will sink, rip apart into countless bits, or get pulled into the skimmer. Check the basket daily to ensure plastic hasn’t clogged the skimmer’s inlet.
  • Add a liquid solar blanket. This is a chemical that you can use in tandem with black trash bags. Simply follow the instructions for how much to add to help reduce water evaporation and retain more heat.

The verdict on black trash bags for pool heating

I feel that black trash bags create more problems than they solve. Many pool owners who were not careful to follow the steps outlined above have had their pool pumps and filtration systems clogged due to deteriorated plastic bits.

Perhaps black trash bags are effective for a few days, but then they start falling apart and creating a big mess. How about using a more effective pool cover instead?

Solar pool covers or solar rings are better options

Pool covers and solar rings are able to cover your pool and trap heat far more efficiently than black trash bags.

You could get a black pool cover to absorb lots more heat and trap it in the water. Some people opt for a transparent black cover which not only attracts heat, but lets more sunlight pass into the water, heating it more efficiently. In other words, you get the best of both worlds.

Here are a few tips to keep in mind when picking out a pool cover:

  • The cover color matters. Many prefer dark blue because it is the most aesthetically pleasing while absorbing as much heat as black. A clear black cover can also be great because it can make your pool look like a mirror under the sunlight. Clear gray colors come in third place because they don’t absorb as much heat as dark blue or black.
  • Cover thickness is more important than color. Look for a solar cover that is closer to 14 mil in thickness, rather than the minimum of 10. The difference in heat retention between a 10 mil and 14 mil cover is about 15%.
  • The solar cover’s bubbles should point down. One side of a solar cover looks like bubble wrap. That’s the side that should face down. The bubbles are great at absorbing and distributing heat, hence why it should be touching the water.

I don’t have much to say about solar rings. They are certainly better than black trash bags, but I think a solar cover is far more efficient than it.

Lastly, it’s better to leave your pool uncovered during the day so that it can absorb the most direct sunlight, and then cover it up once it gets colder so that the solar cover can trap the heat throughout the night until the next day. Besides, you’re probably swimming in the pool during the day anyways.