Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
6/9/00
Contacts:
Tom Glanville, Extension Agricultural and Biosystems
Engineering, (515) 294-0463, tglanvil@iastate.edu
Shawn Shouse, ISU Extension Wallace Center, (712) 769-2600,
sshouse@iastate.edu
Elaine Edwards, Extension Communication Systems, (515)
294-5168, eedwards@iastate.edu
Water Tanks Ease Burden on Wells
AMES, Iowa -- As drought conditions linger in parts of the state, some Iowans are noticing reduced water output from their wells. "Wells that tap small, shallow aquifers rely on frequent rainfall to recharge them," said Tom Glanville, Iowa State University Extension agricultural and biosystems engineer. "During periods of drought stress, these types of wells are the first to fail." According to Glanville, a practical and effective strategy for dealing with reduced well output must recognize the importance of water quality as well as quantity.
Wells that are going dry often can provide a small amount of water on a daily basis. If a well normally supplies water that is bacterially safe, Glanville recommends reserving this water for human consumption. Bulk water hauled from other sources is likely to pick up dust and bacteria during transport, calling for extra precautions to keep it bacterially safe. As a result it's often easiest and safest to use well water or bottled water for human consumption, and to use hauled water for livestock, toilet flushing and other uses that do not require bacterially safe water.
Use it ... don't lose it
Although the first response to a failing well may be to contact a local water hauling firm and arrange to have water dumped into the well, this is only a temporary solution. As water inside the well rises above that in the aquifer that supplies the well, water flows out the bottom of the well into the aquifer. Much of the water dumped into the well is wasted since the pump intake is not low enough to recover it.
To ensure that all water hauled and paid for will be available for use, have bulk water deliveries stored in clean, water-tight tanks. "To be sure that chemical contamination does not occur during storage, water should be stored in tanks that have been used only for water. It is extremely difficult to remove chemical residues from tanks that have been used for pesticides, fuel or other potentially toxic substances," Glanville advised.
Water for human consumption
If water temporarily stored in tanks must be used for direct human consumption, food preparation or sanitizing dishes and eating utensils, extra precautions must be taken to make sure that it remains safe to drink. Storage tanks must be thoroughly sanitized prior to use, and a chlorine residual of about 0.5 milligrams per liter should be maintained in the stored water at all times.
Start the sanitation process by flushing obvious dust or other debris out of the tank. Interior surfaces of the tank and lid can be disinfected by washing them down with a solution of one quart ordinary household bleach (unscented, containing 5 percent sodium hypochlorite) in five gallons of clean water. Use relatively small storage tanks because they can be tipped or rolled to make sure the disinfecting solution contacts all interior surfaces. Be sure to empty the strong disinfecting solution from the tank before filling it.
Since naturally-occurring dust and bacteria are likely to enter the tank during filling, a small chlorine residual should be maintained in the stored water, just as it is in public water supplies. To achieve the desired level of chlorine, add one ounce of ordinary chlorine bleach to each 1,000 gallons of water. Since chlorine slowly escapes from standing water, it may be necessary to add additional bleach every few days to maintain the residual. Chlorine test kits are the best way to confirm that the desired chlorine level is being maintained.
To avoid unsafe levels of nitrate and other non-bacterial contaminants found in some water supplies, residents relying on hauled water for human consumption should be sure to inquire about the source of the water delivered to their home. Only accept water from public water supplies, and deal only with experienced water hauling firms that have the equipment and training to deliver safe water.
Stored water for other uses
Water used only for purposes other than human consumption, such as laundry, toilet flushing and other general household cleaning, does not need to be treated with chlorine. Also, livestock are rarely bothered by moderate amounts of bacteria in their water, so stored water does not need to be treated with chlorine for animal use. However, water used for animals should be free of debris and potentially toxic chemicals.
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