The Most Common Waterborne Microbes & How to Filter Them

A quick-reference guide to what’s out there, where it comes from, and how to protect your health.

Microbe

Source

Health Risks

Effective Treatment

E. coli

Animal or human feces (often roof runoff or poor tank hygiene)

Diarrhea, vomiting, kidney strain

Ultrafiltration (0.01 micron), UV, boiling

Giardia (protozoa)

Animal waste near catchments or in tanks

Chronic gut issues, fatigue, malabsorption

Ultrafiltration, UV, boiling

Cryptosporidium

Contaminated water or runoff

Diarrhea, dehydration, long-lasting symptoms

Ultrafiltration, boiling (UV may be less effective)

Campylobacter

Common in NZ — often via bird droppings on roofs

Gut infection, fever, cramping

UF, UV, boiling

Salmonella

Floodwater or fecal contamination

Gastroenteritis, nausea, fever

UF, UV, boiling

Shigella

Human sewage contamination

Intestinal infection, severe diarrhea

UF, UV, boiling

Legionella

Warm, stagnant water in pipes or tanks

Respiratory infections (Legionnaires’ disease)

UV, avoid stagnant hot water, regular flushing

Pseudomonas

Biofilms in pipes, tank slime

Can infect wounds or lungs (rare in healthy people)

UF, regular system cleaning

Mycobacterium spp.

Plumbing systems, tank residues

Respiratory irritation (in immunocompromised)

UV + regular system maintenance