Health problems from pool water
How does pool water get contaminated?
Killing the germs
Public wading pools
Home wading pools
How to reduce the risk
Swimming pools can be lots of fun and a great way to cool down in summer, but people can get sick from germs they pick up from pool water, especially if the pool water is not properly cleaned and maintained. Recreational water illnesses are spread by swimming in the contaminated water, and are caused by several different types of germs, such as bacteria (cryptosporidium, giardia, E. coli and shigella), viruses (entero-viruses) and amoebae.
The chemicals in pools are very effective in quickly killing most of the germs that find their way into the water. However, sometimes the germs are not killed quickly enough (especially when many people are using a pool) and possibly harmful germs can be spread.
Bacteria from the poo of people who are unwell, especially if they have diarrhoea (runny poo), can cause illness if the germs are swallowed with pool water.
Other bacteria can cause ear, eye, throat and chest infections.
Viruses can cause a range of illnesses, including gastro-enteritis, eye, ear and skin infections, and hepatitis A.
Rarely, amoebae can cause a form of meningitis which can be fatal.
People can also get health problems, such as eye and skin irritation, if the chlorine levels are too high or too low, or if the water temperature is too high or too low.
If a child or adult with diarrhoea goes swimming, germs may get into the water, because the germs will be on their skin – this can happen even if they have cleaned their bottom well and thoroughly washed their hands. If a young child who is not toilet trained has diarrhoea, it is quite likely that the child will poo in the water.
If an unwell child’s nappy is changed on the ground or on a table near to the pool, it is possible that germs will get onto the surfaces and be carried into the pool.
If a person has any other health problem, such as an eye infection, the germs causing this infection can also get into the water.
If the pool water is correctly treated with chlorine, the chlorine will kill the germs – but it takes some time.
Some bacteria will be killed within an hour, while other bacteria such as cryptosporidium can stay in the water for a couple of days.
It can take longer for viruses to be killed than for bacteria.
Amoebae will be killed if the water is correctly chlorinated.
If the water contains solids such as leaf litter, it can take longer to kill the germs.
People can become sick after swimming in even the best maintained pools, especially if a lot of people use the pool in a short time. Pools that are not kept well can contain a lot of illness-causing germs.
Remember – you share the water with everyone in the pool.
Wading pools are the most likely pools to have large numbers of germs, because they are used by children who are not reliably toilet trained.
Wading pools are also shallower and warmer, with less water – which makes them more easily contaminated.
Since young children tend to swallow water, wading pools can often be the source of infections and illnesses.
The little play pools that people have at home, and fill with water from the garden hose, should be emptied straight after use.
They don't have enough chlorine in their water to stop germs from multiplying.
The water is also a drowning hazard for small children if the pool is left where the children can get to it while not under close adult supervision.
The Centers for Disease Control and Prevention in the USA devised the following tips, the ‘PLEAs’, to protect people from germs in a swimming pool.
‘PLEAs' for all swimmers
‘PLEAs’ for parents of young kids
‘PLEAs’ for general water safety
(Adapted from ‘Healthy Swimming Brochure', updated)