It is often necessary to quickly provide a basic water supply during and shortly after an emergency. This may be because the normal supply has been damaged or destroyed, or because people collect in a place where no water supply exists (a new refugee camp, for example).
Often the quickest way of providing a water supply is to transport water in tankers from a nearby source and store the water in tanks and reservoirs. However it is rare for water tankers and water reservoirs to be readily available in such situations. The most common solution is to hire vehicles and tanks that have been used for other purposes but they must be cleaned and disinfected before they can be used.
Figure 1 outlines a three step approach to cleaning and disinfecting water tanks and tankers. It is an emergency response to disinfect polluted or disused tankers so they can store and transport water of satisfactory quality.
Large quantities of clean water will be required to clean and treat storage tanks and tankers before they can be used to store water.
The tank must be cleaned to ensure that water stored in the tank does not become contaminated by dirt or traces of the substance the tank previously held. This can be achieved by following the three steps below:
Open the outlet valve/tap and drain out any remaining liquid. Collect the liquids so that they can be safely disposed of. Most tankers have their outlet valve at the back, so park it on a slope so that all the liquids can be discharged (Figure 2).
Permanent storage tanks are usually fitted with a washout valve that draws water from the base. Use this for emptying rather than the normal outlet valve. The process of emptying the remaining liquids from portable tanks will depend on the shape and design of the tank. Some can be tipped on their side and others dismantled.
Use a mixture of detergent and water (household laundry soap powder will do) to clean all internal surfaces of the tank. This can be done with a stiff brush or a high pressure jet. If the tank has contained volatile substances such as oil or organic liquids such as milk, try not to enter the tank as the gases given off by the liquids could be dangerous. Attaching the brush to a long pole may make it possible to clean the tank without entering it. Take special care to clean corners and joints so that no small amounts of the original liquid remain. Even minute amounts of some liquids can give the water a bad taste and people will refuse to drink it.
Leave the outlet valve open whilst cleaning and collect the waste liquid for safe disposal.
This is most easily done with a high pressure hose pipe or water jet but if they are not available the tank can be filled with water and left to stand for a few hours. Drain all the water from the tank and collect for safe disposal as before. Continue flushing the tank until there are no longer traces of detergent in the water.
Tank cleaning should be done in an open area away from houses to avoid possible health problems.
Box 1. Chlorine disinfection of a tank
The tank on a water truck needs to be disinfected. The tank is 4 meters long 1.8m wide and 1.4m high (the tank is oval shaped).
The total volume of the tank is:
Therefore add slightly more than four, 20 litre buckets of chlorine solution as you fill the tank with clean water.
Care must be taken when disposing of liquids from containers. Sudden discharge of water will cause localised erosion or flooding. Make sure the water is channelled into a natural water course such as a river, gully or lake.
If the tanker has been used for carrying other liquids, special arrangements must be made to prevent environmental pollution.
One disposal option is to collect the waste liquid in a temporary pond and then mix the liquid with sand. The mix can then be transported to a suitable site (such as a land fill site) for disposal.
If there are large quantities of waste liquid, absorbing them into sand is not possible. In that case a vacuum tanker (such as one used for emptying septic tanks) will be needed to remove the liquid for safe disposal.
Gaining access and working inside a water tanker can be difficult and dangerous. Frequently there is only a small access hatch on the top of the tanker through which to get in and out. Cleaners should be aware that some liquid carried in tankers can give off dangerous gases which may remain even when the liquid has been removed. The liquids may also cause physical dangers such as falling on slippery surfaces or burning from corrosive liquids.
Always blow fresh air into the tank for a period before allowing a person to enter the tanker. The cleaner should wear protective clothing, including gloves, boots, a hat and glasses.
Make sure someone remains outside, next to the access hatch all the time someone is working inside in case there is an accident. The availability of gas masks and portable ventilators would be an advantage.
Davis, J. and Lambert, R. (2002) Engineering and Emergencies A practical guide to fieldworkers, 2nd Edition, ITDG Publishing, UK.
Source: World Health Organisation
Also see Cleaning and Maintaining Water Storage Tanks. In emergency situations it is often not possible to be too discerning when it comes to using a water tank or water tanker that has had other substances in it before. In normal situations, we do not recommend using water tanks or water tankers that have stored substances other tank water for potable uses. JoJo Tanks in South Africa manufacture a wide range of water storage tanks and are made with an inner FDA-approved, food grade lining that keeps stored water fresher for longer and inhibits algae growth. If tanks are required for storing chemicals and fuel, we recommend that medium- or heavy duty versions of the various tanks be chosen (in the vertical JoJo tank range, these are known as ‘chemical tanks‘). Click on the links below to view the wide range of JoJo water tanks, JoJo chemical tanks, JoJo horizontal tanks (for water tankers and chemical tankers) JoJo tank stands, and other high quality JoJo Tanks products.
JoJo Tanks South Africa offer a wide range of plastic water tanks and chemical tanks to suit every household, business or agricultural need, including silo tanks and silo tank stands. See JoJo Tanks VERTICAL TANKS, HORIZONTAL TANKS (transporter tanks), STEEL TANK STANDS and OTHER JOJO PRODUCTS. Also see JoJo Tanks’ NEW 6000 LITRE UNDERGROUND TANKS. Also see our FAQ and WATER TANK PRICES.
JoJo’s superior polyethylene plastic water tanks and steel water tank stands make JoJo Tanks the leaders in plastic water tank technology and the quality, affordability and guarantee on these water tanks make JoJo products the best choice in South Africa. JoJo’s water tanks and chemical tanks come standard with a number of features that are often lacking on cheaper/inferior plastic tanks made by other companies in South Africa.
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