Both are found in human and animal faeces - if just a trace of infected faecal matter gets into a person's mouth, they can be infected. That's why careful handwashing with warm water and soap is important after using the toilet or handling pets or babies' nappies. It's also important to avoid drinking water from creeks, rivers or dams. Anyone with diarrhoea should stay out of swimming pools to avoid contaminating the water. That's up to you - if you do, follow the instructions for maintaining the filter carefully.
Some people use a water filter to remove any chlorine taste from the water.
You can also remove it by leaving a jug of water in the fridge overnight. But it's not a good idea to leave drinking water at room temperature for more than a few hours - it may grow germs. Some people think that filtering tap water through gauze or cotton wool removes harmful bacteria - but this may encourage bacteria to grow on the cotton wool or gauze and may contaminate the water. It's best not to - it may contain metal from the heating element. This may be a problem with the plumbing.