In 2019 in England and Wales, just over 60% of the water supplied to the public was from surface water sources, such as rivers and reservoirs. The sources of water contain normal, aquatic life, such as Algae and animals.
When this water is treated, the vast majority of these animals and plants are removed, through the various stages of water treatment. However, there are some occasions when water treatment is not as effective as it could be, and animals and algae can enter the water distribution network.
These animals and algae are normally not visible to the naked eye, however certain species such as Asellus (fresh-water shrimps) or Chironomids (midge fly larvae) are slightly larger and may be seen without a microscope.
These animals are harmless and do not pose any risk to human health. They are part of the natural environment and an essential part of the ecosystem. Indeed, many are ‘indicators’ of healthy, good quality rivers, lakes and streams.