Tomos Llewellyn
The Romance of a Clear Spring
There is something deeply appealing about a spring. You come across it on a walk — a trickle emerging from mossy rock, a stone trough beside a bridleway, a pool so clear you can count the pebbles on the bottom. Surely water straight out of the ground is purer than anything from a tap?
It isn't. A spring is only as clean as the ground it has travelled through and whatever has been grazing, defecating or decaying upstream. Clarity tells you almost nothing about safety.
Clear Water Is Not Clean Water
We judge water by sight and smell, and both are unreliable. The pathogens that cause the most trouble in UK waters are invisible — measured in microns, not visible specks. A spring can be crystal clear, icy cold, tasteless and still carry enough bacteria or parasites to put you in bed for a fortnight.
Unlike a treated mains supply, a wild spring has no filtration, no chlorine residual and no one checking what enters it a hundred metres uphill. Groundwater also moves. What emerges at a spring may have fallen as rain weeks or years earlier, and may have passed through farmland, old mine workings or a leaking septic system on the way.
What Is Actually in the Water
The contaminants found in untreated spring and surface water fall into a few broad groups:
- Bacteria: E. coli, Campylobacter and Salmonella are common where animal or human waste has entered the water. They cause vomiting and diarrhoea, sometimes severe.
- Protozoan parasites: Cryptosporidium and Giardia catch people out most often. They resist chlorine, survive for months in cold water, and a tiny dose can cause weeks of illness.
- Viruses: Norovirus, hepatitis A and others persist in water and are small enough to pass straight through many filters.
- Agricultural pollution: Nitrates, phosphates and slurry runoff are widespread. If there is livestock in the catchment, treat the water as contaminated.
- Heavy metals: Old lead mine workings, particularly in Wales, Cornwall and the Pennines, can leach lead, arsenic and cadmium into springs. You cannot see, smell or boil these away.
- Blue-green algae: Not a true algae but cyanobacteria, which can produce toxins. It often looks like green paint or pea soup along the water's edge.
Then there is Leptospira — the bacterium behind leptospirosis, or Weil's disease — shed in rodent urine and able to enter through cuts, grazes and the membranes of the mouth, nose and eyes.
Ancient Wells and Holy Springs
Britain is dotted with wells used for centuries: holy wells, wishing wells, chalybeate springs at old spas, and village pumps with a plaque and a bit of legend. They are wonderful things, part of our landscape history, and many are lovingly looked after by local groups.
But heritage is not a hygiene certificate. Many old wells are shallow, unlined or cracked, and collect surface runoff from the surrounding land. Some sit near churchyards, roads, farms or field drains. Several were historically valued for their mineral content — which is another way of saying the water is heavy with dissolved metals. A well that has been the local beauty spot for four hundred years may also have been the local source of stomach upsets for four hundred years.
Enjoy them, photograph them, read the plaque. Take your drinking water from somewhere else.
Wild Swimming: Enjoy It, Don't Swallow It
Wild swimming is a different matter, because you are not setting out to drink the water — but you will inevitably take some in. That is fine for most people most of the time, and the benefits of cold water swimming are real. A few habits reduce the risk:
- Avoid swimming for 24 to 48 hours after heavy rain, when runoff and sewage overflow are at their worst.
- Cover cuts and grazes with a waterproof dressing, and rinse off afterwards.
- Try not to swallow, and keep your head above water where you can.
- Check for blue-green algae before getting in, and stay out if you see it.
- If your immune system is weakened, or you are pregnant, take extra care and check current advice.
How to Make Wild Water Safe
If you do need to drink from a wild source, treat it. The most reliable method is boiling: bring the water to a rolling boil and keep it there for at least one minute. That kills bacteria, viruses and parasites. It does nothing about lead, arsenic or other dissolved chemicals.
Filters help but need reading. A filter rated to 0.1 micron, or an absolute 1 micron filter, removes protozoa and most bacteria, but not viruses and not dissolved metals. Chemical tablets work against bacteria and viruses but struggle with Cryptosporidium. UV purifiers are effective against all three if the water is clear; silt and cloudiness reduce their performance.
The safest approach is a combination: filter for clarity, then boil or use UV, and never choose a source downstream of farmland, mine workings or obvious pollution.
One simple rule covers almost everything here. Treat wild water as something to enjoy, respect and look at — not something to drink straight from the ground. Carry your own water. If you must drink from a spring, treat it first. The view tastes just as good.
