Wild swimming in the UK has grown rapidly in recent years — from rivers and lakes to coastal dips and open water swimming spots.
But while wild water feels freeing, it is constantly changing.
Testing water quality before swimming can help you make informed decisions about where and when to enter the water — especially in rivers where conditions can shift quickly.
Recently, we tested the same stretch of river at multiple entry points just metres apart and I was amazed at what we discovered.
Same day. Same conditions. Different results. At one location, ammonia levels on our reading was noticeably higher.
That small change highlights something important:
Water quality is not uniform — even within the same swim spot.
How Water Quality Can Change in Rivers and Lakes
Water conditions can vary due to:
- Heavy rainfall washing agricultural run-off into rivers
- Animal waste entering upstream
- Decomposing organic matter
- Low river flow concentrating pollutants
- Urban drainage or road runoff
For wild swimmers in the UK, this means that yesterday’s safe-feeling swim spot may not look the same today.
Even within the same river, water can test differently:
- Around bends
- Near inflow pipes
- In slower-moving sections
- Downstream from farmland
- Close to marinas or bridges
Testing different entry points helps build a clearer understanding of your specific swim location.
What Does Ammonia in Water Indicate?
Ammonia is naturally present in small amounts in many freshwater environments. However, elevated ammonia levels can suggest recent organic pollution.
This may be linked to:
- Agricultural runoff
- Animal waste
- Decaying plant matter
- Reduced dilution during dry periods
- Wastewater discharge
- Combined sewer overflows (CSOs)
Higher ammonia does not automatically mean unsafe swimming conditions, but it can indicate that something upstream has changed — particularly after heavy rain.
Understanding these indicators allows wild swimmers to assess risk in real time rather than relying solely on delayed laboratory reports.
Why Real-Time Water Testing Matters for Wild Swimmers
Many official water quality tests are laboratory-based and published days later.
By the time results are available:
- Rainfall may have altered conditions
- Tides may have shifted coastal water
- Flow rate may have changed pollutant concentration
For those who swim spontaneously or regularly in rivers and lakes, waiting days for updated data isn’t always practical.
Testing at the water’s edge provides insight into that specific moment.
Not last week.
Not after the rain has passed.
But now.
How SwimSense Supports Informed Wild Swimming
SwimSense water testing strips were developed specifically for wild swimmers and open water swimmers in the UK.
They:
- Provide water quality readings in minutes
- Are affordable enough for regular testing
- Fit easily into a swim bag
- Allow comparison between different entry points
They are not designed to replace official environmental monitoring, they are designed to empower individual swimmers with accessible, real-time awareness.
Wild swimming should feel confident, empowering and informed — not uncertain.
Building a More Informed Wild Swim Community
As more swimmers begin testing their local wild swim spots, patterns become clearer:
After rainfall.
During low river flow.
Near agricultural land.
Around urban runoff points.
Awareness builds through shared knowledge. Wild water will always move and change.
But informed - swimmers can move with it.
If you’d like to explore how SwimSense works, or begin testing your own wild swim spots, order your kit today, or contact us at Sundfoerr. We are looking at how we can start sharing readings amongst our swimming communities so watch this space!
Swim informed.
Swim empowered.
Swim wild.
Neets xx
