Rivers and lakes are generally quite safe for swimming (or for falling in!).  Bacteria are usually at very low concentrations which do not cause health problems.   But some bacteria can cause infectious diseases, particularly when found in higher concentrations, for example as a result of storm overflows.  It’s important to be able to recognise the symptoms and take appropriate precautions.

Although the main concern for rowers focuses on leptospirosis (Weil’s disease), there are several other infectious diseases which can be contracted through contact with water or through rowing:

Leptospirosis/Weil’s Disease

Leptospirosis affects around 40 – 50 people in Britain each year, and can be fatal if not recognised. It is usually associated with stagnant or slow-flowing water, but can also be found in rivers and lakes where rowing takes place. In the early stages Leptospirosis can be mistaken for flu; typically early symptoms develop between 7 – 14 days after infection, although in rare cases the incubation can be as short as 2 – 3 days or as long as 30 days. Infection is usually through an open cut or blister; if you develop flu-like symptoms after rowing go to your GP and say that you are a rower.  Treatment is with antibiotics, which should be administered early.

Blue-Green Algae / Cyanobacteria

Cyanobacteria are usually found in late summer, after extended periods of warm, settled weather, and are most common on lakes (e.g. 2000 metre courses) and other slow-moving water. The bacteria can be blown in the wind as well as being picked up by direct contact with the algae, and can be fatal to smaller animals including dogs. In humans they can cause eye irritation, dermatitis and joint/muscle pain or, more seriously, gastro-enteritis, pneumonia, liver damage and certain neurological conditions.

Gastro-intestinal illness

Illnesses caused by contact with sewage are most common in slower-moving rivers, but can affect other rivers, including the Thames, at times of flooding or close to water treatment outlets (e.g. half-way up Desborough Island and on the Molesey Reach below Sunbury Lock).  Walton RC is now taking part in a monitoring project to measure concentrations of bacteria on our reach.


The precautions you should take in all these cases are the same:
– Clean blade-handles and scull-grips after use

– Wash your hands before and after outings
– Wash or shower after rowing
– Cover minor cuts and scratches with waterproof plasters before getting into the boat
– Clean open wounds, such as blisters or calf abrasions, with an anti-bacterial cream or spray
– Wear trainers (or, on the Tideway, boots) to avoid scratches and cuts on the landing-stage
– Do not share bottles or glasses with your crewmates – always use your own
– Avoid drinking river water – if you do capsize or fall in, keep your mouth closed