Safe swimming: what's lurking in the water?

More and more of us, it seems, are rediscovering the pleasure of open water swimming. But bathing in the sea, lakes, streams, ponds or rivers can be risky to your health unless you take sensible precautions.

Here’s how to make sure you don’t catch or encounter anything nasty when taking the plunge.

Before you take the plunge

Five tips from the River and Lake Swimming Association:

Jellyfish stings

Jellyfish are responsible for the most stings in the sea around the UK and the problem is set to worsen as jellyfish numbers rise. UK jellyfish stings aren’t dangerous, but they can lead to an intense, stinging pain, sometimes with itching and a rash.

Shark attacks

Believe it or not there are at least 21 types of shark in British waters including the Catshark, Blue Shark and toothless, plankton-eating Basking Shark. But don't worry, it really IS safe to go in the water. According to the Shark Trust, shark attacks are incredibly rare with many more people killed or injured each year by bee stings, snakes, crocodiles or tigers.

The Trust adds that you're highly unlikely to encounter a shark during a trip to our seaside. In any case, most British sharks are completely harmless with only two reports of unprovoked attacks by sharks in European waters since 1847.

Tummy upsets from sewage in the sea

Swimming in sewage-contaminated sea water can cause a range of illnesses from gastrointestinal (digestive tract) and respiratory infections to ear, nose and throat complaints.

Many beaches in Britain have excellent water quality, others less so. The amount of sewage contamination varies from beach to beach.

What to do: To minimise the risks of swimming in polluted water, pick a Blue Flag beach or one recommended by the Marine Conservation Society (MCS). The Good Beach Guide is published by the MCS and indicates which UK beaches have excellent water quality.

Find out how to find clean sea water to swim in.

Getting too cold

Outdoor swimming in cold water saps your body heat so your arms and legs get weaker and you could get into trouble if you’re unable to get out.

What to do: If you’re not used to swimming in cold water, the Outdoor Swimming Society recommends that you wear a wetsuit for anything more than a quick dip. It also advises that you:

Shivering and teeth chattering are the first symptoms of hypothermia. If that happens, get out of the water and warm up. Read more about treatment for hypothermia.

Blue-green algae

Blue-green algae can appear on lakes and ponds over summer, forming a powdery green scum. Swimming in it can trigger skin rashes, stomach upsets and sore eyes.

What to do: Avoid swimming in lakes that have areas of blue-green algae.

Finding clean freshwater spots

Our rivers and streams and lakes are less polluted with chemicals and germs from sewage spills and animal waste than they’ve ever been. But not all of them are clean enough to swim in and could trigger stomach upsets and infections.

What to do: Generally, if the water looks clean and clear, it’s a good indication that it’s safe to swim in. If it’s scummy or cloudy, it’s best to avoid it.

The Environment Agency monitors the water quality of our rivers, streams and lakes regularly at over 7,000 locations. The Agency’s website can give a water quality rating for the stretch near you when you enter your postcode into their site.

Weil’s disease

Weil’s disease (also known as leptospirosis) is a bacterial infection spread by animal urine, especially that of rats. It tends to be found in urban rivers and canals, but you can also catch Weil’s disease in still water such as lakes, either by swallowing contaminated water or, more likely, by getting it into your bloodstream through a cut or graze.

What to do: Cover any cuts with a waterproof plaster before swimming and avoid swallowing the water. Never swim in an urban canal. If you develop symptoms of Weil’s disease within a few weeks of being in water, see your doctor. The condition can be treated with antibiotics.

Read more about Weil’s disease.

Tummy bugs from sewage in streams, rivers and lakes

You can end up with diarrhoea and vomiting after swimming in sewage-contaminated streams, rivers and lakes. The main culprits are bugs such as E. coli and Cryptosporidium, which can be spread by swallowing water from lakes, streams and rivers containing sewage or any kind of animal or bird droppings.

What to do: To reduce your risk of tummy bugs, don’t drink from streams even if they look clear. Cows or sheep may have urinated in them. Wash your hands after paddling in a river or stream and avoid swallowing water while swimming.

Read more about tummy bugs and how to treat them.

Swimmer’s itch

"Swimmer’s itch" (cercarial dermatitis) is an itchy rash caused by certain parasites that live in freshwater snails. The snails live on the reeds around marshy lakes and stagnant ponds. On warm, sunny days the parasites can be released into the water and burrow into the skin of swimmers.

What to do: Although uncomfortable, the itching generally lasts no more than a couple of days. You can’t spread the rash to other people, and it doesn’t need treatment.

To reduce your risk of swimmer’s itch, avoid swimming or wading in marshy areas where snails are commonly found and rinse off as soon as you leave the water.

Plant dangers in the garden and countryside

We’re a nation of gardeners and love walking in the countryside. But rural rambles can bring perils. While most plants that grow in the UK are harmless, some sting, scratch or are poisonous.

Keep your family safe by reading this guide to plant hazards, and find out what to do if someone is affected.

Stinging nettles

One of the most widespread plants in the UK, stinging nettles (pictured left) are the bane of many a country walk, especially for small children. Nettle leaves are covered in tiny, needle-like hairs. When you brush against a nettle, the hairs break off, penetrate your skin and sting you, producing the familiar burning sensation, itch and rash.

According to the Natural History Museum, the old wives' tale that the dock leaf (pictured right) is an effective natural remedy for nettle rash is true. The dock leaf, says the museum, contains chemicals that when rubbed over the sting, neutralise it and cool the skin down.

What to do: If you get stung by a nettle, look out for a dock leaf to rub on the rash. Dock leaves usually grow close to nettles. It’s also a good idea to teach toddlers what stinging nettles look like so they can avoid them.

Giant hogweed

Poisonous plants

Most British plants are harmless, but some – such as the yew, chrysanthemums, Hemlock Water Dropwort, deadly nightshade, snowdrops and mistletoe – are potentially toxic. Their leaves, berries, flowers, fruit, sap or bulbs can poison you, either by making you ill after eating them (as is the case with daffodil bulbs) or giving you a skin rash after touching them.

What to do: Remind children not to eat anything from the garden, unless you’ve said it’s OK. If anyone shows symptoms such as tummy ache, vomiting, rashes or diarrhoea after playing outside, take them to an A&E department immediately with a sample of what they’ve eaten. When picking and eating wild mushrooms and berries, such as blackberries and elderberries, be absolutely sure of their identity beforehand.

Find your local A&E department.

Poison ivy

Poison ivy (pictured left) causes a painful and itchy, blistery rash on your skin if you come into contact with it. The good news is you’re unlikely to experience this nasty skin reaction because we don’t have poison ivy in the UK. It only grows in North America.

English ivy (pictured right) – which is the type that you see climbing walls and in hanging baskets and window boxes – isn’t harmful, although you should still be careful when handling it if you have sensitive skin as its sap can be irritating.

Read about 10 insects that can bite or sting you.

Parsnip plant

Handling the parsnip plant (Pastinaca sativa), which grows wild and is cultivated in gardens in allotments may make your skin very sensitive to light leading to burning, blisters and a painful rash.

The problem seems to be the plant's sap which contains chemicals called furoumarins. These chemicals are absorbed by the skin and can then react with sunlight to cause skin inflammation.

What to do: watch out for wild parsnip in roadside ditches and along railway tracks. If you develop skin irritation or blisters after touching parsnip plants, speak to your doctor.

The Royal Horticultural Society website has advice on how to keep your family safe from potentially harmful garden plants. You can also call its helpline on 0845 260 8000, from 10am to 12.30pm and 1.30pm to 4pm.

Read about 10 insects that can bite or sting you.

12 UK insects and bugs that bite or sting

Buzzing bees, marching ants and swarms of midges are as much a part of the British summer as deckchairs, picnics and ice creams.

Wasps

The humble wasp (and closely related hornet) can give a nasty sting if it feels threatened, leading to itching and swelling. And wasp stings aren't always harmless. Stings from wasps cause the most allergic reactions in the UK.

You won't have an allergic reaction after your first sting by a wasp, but you can develop a serious allergic reaction (also known as an anaphylactic reaction) after one or more stings have "sensitised" your system.

Prevent wasp stings: Don't try to swat wasps away. You'll just make them cross and more likely to sting you. Instead, calmly and slowly move out of their way. Like other stinging insects, wasps love bright colours so wear white or neutral clothes to deter them. Look out for wasps' nests in your home or garden and have them removed immediately by your local council or a pest control expert when you find them.

See a doctor if: you develop symptoms of a serious allergic reaction.

Bees

A bee sting feels similar to that of a wasp.

In the UK, we have two types of bees – honey bees and bumble bees.

The honey bee leaves its barbed sting inside you then dies. It's important to remove the barb to stop infection setting in.

Here's how to remove a bee sting.

Bumble bees do not have barbed stings and can sting you many times if they want to. But bumble bees aren't aggressive and are unlikely to sting unless provoked.

Bee stings are painful, but unless you have an allergy to bees, they're unlikely to cause serious damage. If you're allergic to wasp stings, don't assume you'll also be allergic to bee venom. Bee and wasp venoms are different and people who are allergic to wasp venom are rarely allergic to bee venom.

Prevent bee stings: Stay still and calm while a bee buzzes around you. It's a myth that bees love sweet drinks. In fact they can't 'smell' sugar so they're not attracted to sugary drinks. But they don't like certain odours, so avoid wearing perfume or aftershave if you're outside around bees.

See a doctor if: you develop symptoms of a serious allergic reaction.

Ticks

Strictly speaking, these small spider-like creatures aren't insects, but ticks are increasingly becoming an unpleasant feature of strolls through UK woods, moors or thick grass. Once they've latched onto you, ticks cling to your skin and suck your blood. The bite doesn't really hurt, but certain types of tick can transmit a condition called Lyme disease. Therefore, remove a tick as soon as you spot one on your skin.

Prevent tick bites: Wear long sleeves and trousers when you're walking in forested, overgrown areas and use a tick repellent.

See a doctor if: you get a circular rash spreading out from where you were bitten or you develop the symptoms of Lyme disease.

Send any ticks you collect to Public Health England and they'll identify them for you. Find out more about Public Health England's Tick Recording Scheme.

Mosquitoes

Mosquitoes are a nuisance. Their bites cause intense itching and swelling and spoil many a picnic and camping trip. But while they transmit deadly diseases in other parts of the world, they don't cause major harm in the UK.

Prevent mosquito bites: Smells and bright colours attract insects. Avoid using scented hand or body creams and strong perfumes and sparkly, colourful jewellery if you’re going to spend time outside. Insect repellents are also effective. Don't forget to cover up and use repellent at night if you're camping. Read more about how to treat mosquito bites.

Flower bugs

Flower bug may sound innocuous, pretty even, but don't be fooled. Properly known as Anthocoris nemorum, these common predatory insects, which feed on aphids and mites, can take an aggressive bite out of human skin too. The wounds are very itchy and often slow to heal.

You can identify the common flower bug by its tiny oval body, reflective wings and orange-brown legs. Look out for them on flowering plants in meadows, parks and gardens.

Prevent flower bug bites: The common flower bug bite isn't serious, but it's very annoying. You could use insect repellent when gardening or, better still, cover your bare skin and wear gloves to stop them nipping. Flower bugs are great for the garden so don't be tempted to use a general insecticide to get rid of them.

Midges and gnats

Midges (often also called gnats) are the scourge of trips to the Scottish Highlands and a common feature throughout the rest of the UK, especially on damp and cloudy summer days. Midge bites don't transmit illness but they're painful, itch intensely and can swell up alarmingly.

Prevent midge bites: Midges and gnats tend to attack in swarms, especially in hot weather, so use an insect repellent and cover up at dawn and dusk. Protective gear, such as mesh covers for your face, can be very effective too.

Ladybirds

The harlequin ladybird is a recent invader to our shores, but in the space of just a few years has colonised much of the UK. They're bigger, rounder and more aggressive than native ladybirds such as the two spot and seven spot. All ladybirds can nip, but harlequins seem to bite more than others.

How to spot it: The harlequin ladybird can be red or orange with multiple spots. Look out for a white spot on its head – native red ladybirds never have white patches.

Prevent ladybird bites: Wear gloves when gardening, but try not to intentionally kill harlequin ladybirds. It's hard to selectively get rid of them without hurting native ladybirds, and all ladybirds are good for the garden.

Bedbugs

Bedbugs are a growing problem in the UK. They don't carry disease, but their bites cause itchy red bumps. Some people have a serious skin reaction with blisters that can become infected.

What to do: If you think your home is infested with bedbugs (tiny black spots on your mattress and bed are a giveaway), get a pest control expert to treat it straight away. Don't be embarrassed – bedbugs are not a sign of a dirty home. Read more about bedbugs.

Horseflies

A large, hairy fly whose bite can be extremely painful, the horsefly tends to bite on warm, sunny days, especially the head and upper body.

Prevent horsefly bites: The horsefly doesn't spread disease, but as its bite cuts the skin rather than piercing it, horse fly bites are very painful, take longer to heal than other insect bites and can easily become infected, so cover up and use insect repellent. Read what to do if you have an infected insect bite.

Ants

Our most common ant, the black garden variety, doesn't sting, but the UK has red, wood and flying ants that do, especially in warm weather or when threatened. You'll feel a nip, but it's all pretty harmless as ants have less toxin in their sting than wasps or bees. The only evidence you've been stung will probably be a pale pink mark.

Prevent ant stings: Use over-the-counter ant repellent.

Spiders

You may be surprised to know that a number of spiders in the UK are capable of giving a nasty nip – usually after rough handling or if they become trapped in your clothes. You can tell it's a spider bite because it leaves little puncture marks. According to the Natural History Museum, false widow spiders, so-called because of their similarity to the more poisonous black widow spider, are the main culprits and typically give bites that cause pain, redness and swelling.

Prevent spider bites: Don't disturb spiders if you can help it – they tend to bite you only when they feel threatened.

Read more about insect bites and stings.

Caterpillars

The caterpillars of oak processionary moths are a real pest. They were first found in the UK in 2006 and are now in London and parts of southeast England.

In late spring and summer, the caterpillars have thousands of tiny hairs that can cause itchy rashes, eye problems and sore throats – and very occasionally breathing difficulties. The caterpillars walk up and down trees in nose-to-tail processions. If you find them, or spot one of their white silken nests, report it to the Forestry Commission or to your local council.

Prevent oak processionary moth problems: Don't touch or approach the caterpillars or nests. Don't try to remove the nests yourself – call a pest control expert.

If a caterpillar is on your skin: Use tweezers or a pen to remove it. Try not to disturb it (for example, by brushing it with your hands) as it will then release more hairs.

If you think you've been exposed: Rinse with running water, allow to air dry and then use sticky tape to strip off any leftover hairs. Use calamine, ice packs or a remedy from the pharmacy containing 3.5% ammonia to relieve the itch. Remove all contaminated clothes and wash at as a high a temperature as the fabric allows.

Don't towel yourself dry after rinsing or use creams containing antihistamine.

See a doctor if: you develop symptoms of a serious allergic reaction or breathing difficulties, or think you may have caterpillar hairs in your eyes. If itching is severe or prolonged consult a doctor or pharmacist.