If UV-C for pools is so great, why not stop using chlorine altogether?

For the past few years, treatment of pool water with chemicals has been subject to a lot of negative attention. It is proven that chlorine and its byproducts are harmful in different ways. UV light to treat pool water is a good way to reduce chlorine as a pool water sanitizer. Yes; I say reduce — not replace. But if UV-C for pool disinfection is so great, why not stop using chlorine altogether?

The short answer to this question, is: UV treatment does not add anything to the water to prevent further new infection.

Now, let’s explain this a little bit more thorough.

Pool water flows through a UV treatment chamber where any dangerous pathogens are inactivated. Therefore the water gets disinfected. It is, however, not disinfectant. The water from the UV chamber returns to the pool, where it will remain for a couple of hours until it is treated with UV light again. If in the meantime bathers go into the pool and leave any pathogens there, the pathogens would not be treated until the water arrives back at the UV treatment unit in several hours’ time. This may form a threat to the health of pool users.


That’s why it is always necessary to maintain a small residual concentration of a secondary disinfectant (such as chlorine) in the pool. For public pools, in most countries, this is in any case even a requirement imposed by the regulatory public health authorities.

The addition of a secondary disinfectant ensures that the water in the pool is disinfected and remains disinfectant. Thanks to the use of UV and a small residual concentration of chlorine, the concentration of chemicals in the pool water can be significantly reduced. Most of the disinfecting will be the work of the UV system.

In particular, the destruction of harmful pathogens and the significant reduction of unpleasant chloramines in the pool water would be handled by the UV system.

No matter which way you look at it, the market is demanding a chlorine alternative.

Pool owners and installers are more aware of the risks of chemicals in pools and have the need for a cleaning method that’s:

  • Favourable for people’s health
  • Better for the environment
  • Not affected by increased regulations around transport and storage of chemicals

Luckily, a method like that is on the rise: UV.