When Should I Change My Hot Tub Water?

Changing hot tub water is a tedious task that most of us tend to push off until it’s absolutely necessary. This chore is especially difficult in the winter time with freezing weather, so making your hot tub water last for as long as possible is crucial. 

There are several factors that play into the length of time for which you can keep your hot tub water. In most cases, your water will last 4 – 5 months before you must change it. Although this is a general guideline, it doesn’t mean that you can’t extend the life of your water. 

Frequency of Use

Chemically, what governs the life of your water is something called TDS – Total Dissolved Solids. This tells you how much chemical and extraneous solids have been dissolved in your hot tub water. The ideal range is between 0-1500ppm. The more frequently you use your hot tub, the faster this number climbs. Once you hit the 1500ppm mark, you must switch out your water because balancing your chemicals will become difficult.

Although the TDS is directly related to chemical use, we do not recommend you stop using chemicals in order to extend the life of your water – this would do the opposite. We recommend you rinse your bathing suit before using your tub. 


Filtration, alongside chemicals, is what keeps your water clean. Be sure that your circulation setting on your tub is high enough for the frequency in which you use it. The more you use your tub, the higher the setting should be. Additionally, the state of your cartridge filter determines the quality of the filtration. To extend the life of your water, we recommend keeping your cartridge filter clean. You can do this by power washing your existing filter or by purchasing a new one here at Valley Pool and Spa.  


The appearance of the water is also a factor that determines whether or not you change it. Sometimes, you just can’t get rid of the cloudiness. If this is the case, your best option is to change the water. Though, the way to prevent cloudiness and to keep your water fresh is by using shock (Aqua Easy Shock or Aqua Brite Plus) on a minimum of a weekly basis. Depending on your spa and the frequency in which you use it, you might need to shock your water more often. We recommend shocking immediately after large groups use the tub to you prevent cloudiness, thus extending the life of your water. 

Tip: Partial Drain and Fill

If you don’t have time to do a full drain and fill, a half drain would do the trick. This would free up some of the TDS, making your water last longer.