Rainwater can provide a supplemental water source by catching and storing it for later use. Rain barrels store rainwater captured from the roofs of buildings. Such systems offer benefits such as reducing your water bill and relieving pressure on wells or municipal water providers, but you must prevent rainwater from stagnating. Stagnant water, characterised by a murky appearance or a surface scum, a foul odour, overgrowth of algae and the decay of organic matter, is a breeding ground for disease and mosquitoes. Basic precautions can help keep your collected rainwater from stagnating.
Use your rainwater as often as possible to keep it from stagnating. Empty your barrel every 10 days, if possible, to prevent the breeding of mosquitoes, which takes about 10 days, if you cannot seal out mosquitoes.
Use a dark coloured, food-grade barrel that is approved for liquids. Keep as much sunlight as possible off the barrel to prevent growth of algae or bacteria.
Cover your barrel with a tight-fitting top. Keep organic matter, such as leaves and twigs, out of the water by using a fine screen at the end of the downspout that feeds your barrel from your gutters to discourage decay of matter in the stored water.
Clean your gutters and roof regularly. Keep the catchment area for your rain barrel free of organic matter and debris.
Add to your barrel non-toxic mosquito dunks, which release a biological agent into the water that is toxic to mosquito larvae but safe to use on your garden, landscaping or even for watering animals.
Clean rain barrels regularly using vinegar, which will kill much of the contamination in the barrel but is not harmful to your garden or animals.
You can add two or three inexpensive goldfish to your rain barrel to combat algae growth. However, you will have to find a balance between keeping your water from stagnating and ensuring the fish have enough food.
Any standing water is a potential drowning danger to small children. Keep barrels tightly covered at all times. If you notice mosquitoes around your barrel, drain it and clean it thoroughly. Mosquitoes can transmit diseases.