Hot weather will trigger an increased need for testing of bacteria in water. Bear in mind:
- Low rainfall, coupled with warmer weather, can lead to a higher than usual bacterial count.
- Higher evaporation levels will mean less water available to dilute the bacteria present in water.
- It is vital to test the water for bacteria, to ensure the safety of plants, fish, humans and animals. Gastro-intestinal problems and diseases such as cholera and typhoid can result from a higher bacterial load in water
- The most common bacterial tests in water that can be performed are for Coliforms and E.Coli
- Test samples must be placed in cooler bag on ice immediately after collection
- Surface water for irrigation also requires that certain precautions be taken
- Drinking water should contain zero Faecal Coliforms and E.Coli
- Bacterial counts are in CFU’s or Colony Forming Units
- Bacterial counts of less than ten will cause some problems, counts between 10 and one hundred will cause infection to all users
- Clean surface water commonly has a count of 1 to 10 per 100 ml – this can increase to as much as a million in sewage water
- When it does start to rain after a long dry period, research has shown that pathogens are higher in stormwater and in sediments. After heavy rain, wait until the sediments have settled before testing / using the water
How to Test for Coliforms / E.coli:
If Test Results are Positive for Bacteria:
- The water has likely been contaminated by sewage or manure
- Try and find out how bacteria got into the water. Possible sources:
- Groundwater may have been contaminated by surface runoff
- Untreated sewage discharges
- Domestic animals and wildlife
- A layer of bacteria may have developed on the surface of the water
- Don’t drink the water until it has been boiled for 10 minutes or treated with Chlorine (5ml : 20 litres water)
- After investigation or treatment, test a new sample to make sure there is no bacteria present
- Maintain a disinfection system by ensuring that Free Chlorine is constantly 0.2 – 0.5 mg/l
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