Swimming Pool Temperature – What We Recommend

In this article we’ll take a look at how water temperature can affect the swimmer and the pool itself. Firstly, it should be said that there is no ‘right’ swimming pool temperature, but there are temperatures that are suitable for different types of swimming pool use. The pool is also affected by the temperature too, which dictates how well it can operate.

The Pool

Swimming pools use the chemical chlorine to keep the water clean and bacteria-free. However, its effectiveness can be adversely affected by water temperature. The higher the temperature of the water, the less likely that the chlorine can operate properly. This makes it less effective at keeping the water clean as the filters will be worked harder.

Additionally, if the water in an indoor pool is kept very warm, then it becomes easier for bacteria to grow and spread. In fact if the water temperature rises by 10 degrees, micro-organisms will grow up to twice as fast. A warmer pool will also mean algae will grow much quicker, meaning that the pool will need to be cleaned more often than usual.

It should also be mentioned that air temperature is also important for indoor pools. If the room is not heated properly, it could be too cold for swimmers when they get out of the pool. In this case, it is sensible to keep the room temperature roughly the same as the water in the pool.

The Swimmer

The Pool Water Technical Advisory Group has guidelines for the best water temperature for different types of user. Babies and young children should have warmer water than usual, recommended to be around 32°C, with the water for older children taking swimming lessons set to 31°C.

Mother and Child Swimming

However for adults, the group advise that the pool water should be a little cooler. For recreational adult swimming, the water temperature should be kept at 29°C and 28°C for competitive swimming events. This is because it is more comfortable for an adult swimmer – as the hotter they get, the less effective their swimming is, and they will also sweat more. Warmer water can also cause muscle cramps and dehydration, so it is advisable to keep the water cooler for competitive swimming and training.

Be careful not to go too cool though, as colder water can shock the heart. Some swimmers have gone into cardiac arrest because of cold water in swimming pools. Elderly swimmers would therefore benefit from a warmer pool water temperature.

The Heater

The right heater for your swimming pool depends on the size of your pool, the larger the pool volume, the higher output power required by the heater. A heater such as the Poolex Vertigo Fi allows for a gradual start-up of the pump and continuous operation at reduced speed, avoiding any peak in consumption.

The Deep End team can assist you with your heat pump decision, our expertise will ensure efficiency.


As we’ve already seen, the ideal water temperature for swimming pools in the UK can vary according to how a pool is used. You should also remember that the higher the temperature that you heat your pool to, the more expensive it will be to run. We recommend that you identify what you will be mainly using your swimming pool for, whether it be for leisure, exercise or for children. You can then strike a balance between the ideal temperature for usage with the ideal temperature for keeping the pool clean and bacteria-free.