On warm days it is wonderful to take a dip in a puddle or lake. It is wise to first check the quality of the water, because heat can quickly deteriorate it. Bacteria divide more quickly due to the heat and can cause health problems. Which culprits should you keep an eye on? What is the quality of bathing water in the Netherlands and how often are measurements taken?

Article content

• The quality of bathing water in the Netherlands
• Measurements
• Who carries out the measurements?
• Health complaints caused by Weil’s disease, blue-green algae and botulism
• The bathing water in the Netherlands compared to other countries
• The current situation per province

The quality of bathing water in the Netherlands

The quality of Dutch bathing water is not in good condition. Rivers and fens (inland waters) often do not meet the set standards. This has been shown by the annual study into the quality of open bathing water. The research was published by the European Commission, the Bathing Water Directive has been in effect since 2006. The focus is mainly on bacteria and substances in the water that cause health problems in people.

Measurements

During the bathing season, which is from May to October, measurements are carried out biweekly in our country at more than six hundred locations. In 2009, 92.2% of inland waterways met requirements, in 2010 84.3%. The cause of the deterioration is the warming of the water, which causes bacteria to divide more quickly. But agricultural manure and pollution by people and birds are also culprits.

Who carries out the measurements?

• The measurements of inland waters are carried out by the water boards.
• The sea and the major rivers are controlled by the government.
• Based on the results, the province can issue negative swimming advice or impose a swimming ban.

Health complaints caused by Weil’s disease, blue-green algae and botulism

Weil’s disease

• Named after A. Weil, a German internist who lived from 1848 to 1918. It is an infectious disease caused by the bacteria Leptospira icterohaemorrhagiae and Leptospira canicola. Weil’s disease is transmitted to humans through the urine of infected dogs, pigs or rats. The bacteria penetrate through the mucous membranes or through the skin, especially in skin wounds.
• Symptoms : from five to ten days after infection: an acute onset with chills, fever, muscle pain (usually in the calves), headache, nausea, vomiting and a drop in blood pressure. Jaundice due to liver cell damage occurs approximately four days after the appearance of the first symptoms. Bleeding may occur from the mucous membranes of the nose, mouth and eyes, and the urine may also contain blood.
• Treatment : the person must be admitted to hospital, adequate treatment is of vital importance. Most people recover, but the disease can lead to death. The treatment consists of administering medication and sometimes kidney dialysis is (temporarily) necessary. Always go to a doctor immediately if you suspect that you have Weil’s disease, the disease can affect the kidneys and liver.

Blue-green algae/cyanobacterium

• These are bacteria that look like algae. You see green or blue strings or slimy wads floating on the water. It is poisonous to humans. Stagnant, nutrient-rich water in particular attracts blue-green algae. If blue-green algae is detected, negative swimming advice is given. Blue-green algae poisoning only occurs through the mouth, the poison does not penetrate the skin. It is more likely to affect small children, as they are more likely to swallow water through the mouth. This also applies to dogs, who always swim with an open mouth.
• Symptoms : within twelve hours of swimming in water with blue-green algae, you may experience skin irritation, eye irritation, headache, nausea, vomiting, diarrhea, fever, stomach cramps, sore or red throat, earache, runny nose, swollen lips.
• Treatment : the symptoms last for about five days and then disappear. Contact your doctor, as the symptoms may have a cause other than blue-green algae.

Botulism

• This is a poisoning caused by the bacterium clostridinum botulinum. The bacterium thrives best in water that is twenty degrees Celsius or warmer. The disease mainly occurs in waterfowl and fish. They develop paralysis and will eventually die.
• Symptoms in humans: nausea and vomiting are the first symptoms, followed by poorer vision, difficulty speaking and swallowing, lethargy, nausea, vomiting, and the muscles become weaker. Infection in humans is uncommon.
• Treatment : this consists of administering antiserum and possibly artificial respiration. Without treatment, the person may die from paralysis of the respiratory muscles.

The bathing water in the Netherlands compared to other countries

We have bad water in the Netherlands, but also in Belgium, Luxembourg, Bulgaria and Latvia the water meets the guideline values in (relatively) few places. Then you better go to Greece, Malta or Croatia.

The current situation per province

If you want to go swimming, it is wise to check the quality of the water in advance. You can view the current situation per province at www.zwemwater.nl .