Sewage or contaminated water can cause ghastly gastroenteritis. Once swallowed, bacteria or viruses will swim into your stomach and wreak havoc, causing vomiting and diarrhoea.

These horrible events will normally occur 12 to 72 hours after exposure to the bacteria or viruses. Viral infections will often pass quickly, but bacterial infections can drag on up to 4 weeks.

Think it’s unlikely to affect you? Even at a beach that meets European water quality standards, a bather has a 1-in-7 chance of contracting gastroenteritis.

Gastroenteritis is highly infectious, so put yourself in quarantine until it passes if possible.

What are the symptoms?

• Scared to leave the toilet

• Profuse puking

• Assquake

• Gut ache

What can you do to treat it?

For most people, no treatment is required for gastroenteritis, but it’s important you drink plenty of water to replace lost fluids.

If dehydration becomes severe, seek advice from a medical professional.

How can you prevent it?

• Don’t go into the water if it’s abnormally brown

• Avoid surfing during or after heavy rainfall

• Learn where your local sewage outlets are, and avoid them.

• Some water companies and environmental organisations offer sewage alert services.

• If you surf in the UK, try the free Surfers Against Sewage alert app.

To prevent others catching your personal plague:

• Wash hands regularly with soap and water, especially after toilet and before food.

• Clean the toilet with disinfectant after every session, including the handle and seat.

• Don’t share towels, cutlery or utensils.

• If you’ve had no diarrhoea or vomiting for 48 hours, it’s safe to be social again.