Worms in Tap Water

What are they?

If you have discovered small worms in your tap water, you may be seeking advice on how to deal with the problem.

The worms that have been reported to have been found in tap water are midge larvae, flatworms, roundworms (otherwise known as nematodes), and rotifers. 

The typical size of parasitic worms or helmiths, such as flukes, tapeworms, hookworms, ascris, pinworms, trichina worms, and filaria worms is 30-50 microns in diameter. Nematodes have long, cylindrical bodies which have no internal segments. Nematodes in fresh water and in the soil are microscopic. Some can be up to 1 inch long and others are microscopic.

Worms in Tap Water


How do they get into your tap water?

They can enter the water supply via reservoirs, wells, streams, rivers or lakes. They live primarily in stagnant fresh water. 

The reasons cited by water companies for how they enter the supply is that abnormal amounts clog up the filters, allowing worms to enter the supply. 

In other cases, water supply pipelines become very old and rupture at some points.


How does it affect your tap water?

The usual response to this problem has been one of increased reactive maintenance routines by the water company. This typically involves considerable cleaning and disinfection of the supply zone and increased chlorination of the water for a period of time after the event. This often gives rise to frequent complaints about the resulting taste and odour. It should also be noted that chlorine and bleach can be totally ineffective against blood worms in particular.

Worms in tap water have also been known to impart objectionable tastes and odours to water.

Although totally undesirable, it is generally accepted that these are completely harmless and they have been studied for whether they are carriers of the type of disease-bearing bacteria found in the intestines of warm-blooded animals. However, we would advise you do not use the water for drinking and cooking until the problem is solved, just to be safe.


What do do about it?

Run the taps for 15 minutes and report it to your water company immediately and take their advice.

If you have a private water supply, contact us and we can arrange for your water to be tested and treatment systems to be put in place urgently. We have a water testing service.

If you have to drink the tap water, boil the water and allow to cool before consuming it.

it is generally advisable to have filtration for the home to protect your water supply from these types of occurrences.


Contact us on 0330 113 7181 to discuss your water quality issues and speak directly to our experts for advice.


News Reports

Bloodworms found in water supply - BBC, 11 September 2007

Water company fights worm problem - BBC, 6 September 2005

Worms found in hospital water supply - The Hindu, 14 January 2013

Worms Not Only Things Water Holds - Orlando Sentinel, 25 January 2001

Bloodworms Turning Up in Tap Water at Hawthorne Homes - LA Times, 24 September 1993