Removing Bacteria from Your Water
How to Remove Bacteria, Viruses and other Microorganisms from Your Water
Water filters either filter via a "barrier" method - where the filter "mesh" is smaller than the incoming contaminant, so it blocks it.
Or they "zap" ie kill the contaminant. For micro-organisms like bacteria and viruses this is done via Ultravioltet filtration.
Summary / Overview
Here's a quick summary of the problem and what to do about it (you can get into the details below.)
Water can carry various micro-organisms. The most common types are summarised below.
Raw wild water will be full of microrganisms and you defintely want to filter that.
Mains supplied / municiapl water should be safe from microorganisms, but sadly, in the UK, some water companies have let standrads slip and there are occassional failures.
Summary of Your Solutions
You could get one or both of the following
Reverse Osmosis (RO) filters can remove contaminants down to 0.003 microns ie they will block anything larger than this. (What is a micron?)
There is basically no dangerous microorganism smaller than 0.003 microns. So Reverse Osmosis should protect you from every microrganism.
Ultraviolet (UV) filters kill microrgisms. They don't remove them by render the harmless.
Why use both?
The benefit of a UV is that it covers your whole property, while an RO is usually undersink and only serves a special small tap where you take your totally purified water from. (There are whole house RO's but these are expensive.)
If your house water is contaminated then so is your bathing water. You could pick up disease from brushing your teeth! So a UV that filters all your water is a good idea.
But UVs don't remove other contaminants like microplastics - and many others. Think of UVs as a "live cell killer". They don't remove anything else. That's why many people prefer a combination of the two.
For complete water purification, combining RO with UV sterilization ensures removal of all microorganisms and their potential toxins.
See details of our Undersink Reverse Osmosis here.
See details of our Whole House UV's here
The Details
The most common types of microorganisms
Bacteria: Bacterial cells range in size from 0.2 to 2 microns. The thinnest bacteria, spirochetes, are often only 0.25–0.5 microns wide. (More details below)
Viruses are the smallest microorganisms, measuring around 0.02 microns in size. Viruses are only alive inside a host body, and are non-living outside of it.
Algae: Algae cells are between 0.000008 to 0.000079 microns in size. But the only one to worry about, Cyanobacteria, also known as blue-green algae, ranges in size from 0.5 to 100 micrometers in diameter
Fungi: Fungi cells are between 1 to 10 microns in size
Human parasitic protozoa: Human parasitic protozoa cells are between 1 to 50 microns in size.
RO filters are very efficient at purifying water and can remove most minerals, organic molecules, and viruses.
Most common Bacteria
• Escherichia coli (E. coli / ecoli):
• Micron Size: ~0.5-2 microns
• Health Risk: Gastrointestinal distress, diarrhea.
• Salmonella:
• Micron Size: ~0.7-1.5 microns
• Health Risk: Causes salmonellosis, diarrhea, fever.
• Legionella:
• Micron Size: ~0.3-0.9 microns
• Health Risk: Legionnaires’ disease (severe pneumonia).
• Best Water filter to protect you against these are Reverse osmosis (RO) or UV purifiers (to inactivate).
Most common Viruses
• Norovirus:
• Micron Size: ~0.02-0.04 microns
• Health Risk: Severe vomiting and diarrhea.
• Hepatitis A Virus:
• Micron Size: ~0.02 microns
• Health Risk: Liver inflammation, jaundice.
• Rotavirus:
• Micron Size: ~0.07 microns
• Health Risk: Diarrhea, especially in children.
• Best Filters: Ultraviolet (UV) purifiers, reverse osmosis (RO), nano-filters.
Most common Protozoa
• Giardia lamblia:
• Micron Size: ~8-15 microns
• Health Risk: Giardiasis (diarrhea, cramps).
• Cryptosporidium:
• Micron Size: ~4-6 microns
• Health Risk: Cryptosporidiosis (watery diarrhea).
• Best Filters: Ceramic filters, microfilters, reverse osmosis (RO).
Most significant Fungi and Algae
• Cyanobacteria (Blue-Green Algae):
• Micron Size: ~2-10 microns
• Health Risk: Toxins causing liver damage or neurological symptoms.
Best Water Filtration Systems by Contaminant Size
1. Reverse Osmosis (RO):
• Effective for most microorganisms (>0.0001 microns), including bacteria and viruses.
These are common filters, widely in use, so spare parts should be easy to come by - but make sure to get one from a reliable supplier who supplies industry standard parts
2. Ultraviolet (UV) Purifiers:
• Inactivates microorganisms without removing them physically.
These are common filters, widely in use, so spare parts should be easy to come by - but make sure to get one from a reliable supplier who supplies industry standard parts
3. Ceramic Filters:
• Removes bacteria and protozoa (>0.2 microns) through physical filtration.
These are effective IF properly made. They were developed by the Victorians. less widely in use. RO has taken over.
4. Nano - and Microfilters:
• Nano filters (~0.001 microns): Remove viruses, bacteria, and protozoa.
• Microfilters (~0.1 microns): Effective against bacteria and protozoa.
These are effective IF properly made. Make sure they have certification. RO is usually favoured to these.
