Storing water in case of an emergency is a good idea. Having a reserve enables people to weather emergencies and minor service disruptions. A backup source of water is essential for emergency preparedness, three days without water will lead to death from dehydration, but serious and lifelong complications can occur well before you die from dehydration. Did you know that water sometimes needs to be retreated because clean water becomes contaminated? Water typically gets re-contaminated as people use water and they aren’t careful enough to prevent re-contamination, think about when you are washing up, hands are dirty and that leads to contamination of your stored water. Also a lot of stored water is stored for a long time “in case of emergency”. The problem with long term storage is the disinfectant residual deteriorates with time, reducing the water’s ability to prevent bacterial growth.
Preventing contamination is easier than removing contamination. Leave your stored water is a sealed and preferably airtight container. This physical barrier will stop bacteria in the environment from coming into contact with your drinking water. Next is to only open your reservoir with clean hands. Preferably washed with soap and water. It is better to pour the water you need for clean up before you make a mess. This is actually very important when you go to the bathroom, microscopic pieces of fecal matter on your hands will transfer to everything you touch, including the spigot/lid of your reservoir. Bacteria in that fecal matter will travel up the spigot into the water, it will only be a matter of time. Clean hands and routinely cleaning the exterior of your water storage tank/bottle/container/reservoir are essential to prevent contamination.
Another way to help prevent contamination is design of your storage system. Avoid installing a spigot for drinking at the very bottom of the container. Anything left in the water after it is stored will eventually settle out on the bottom, you don’t want this sediment to come out into your glass for drinking. Another design element to consider is to not use a container that is stored with an opening on the top (this isn’t always possible). But think of a 2L bottle, it is filled with an opening on the top but if it is stored on it’s side, the water inside becomes more secure. The problem with openings on the top is that dust and other airborne contaminants settle on top of things in much greater numbers than they do on the side of things. Less contamination near the openings of your water reservoir mean less risk of contamination in your water.
Let’s talk worst case scenario; what needs to be done after your stored backup water gets contaminated with bacteria. Simplest is to throw the water away, wash the container or throw it away. That will solve your problem but don’t always have to be so extreme, it is easier to treat water the second time as there is typically only one form of contamination. The demand for disinfection will be lower. This means less less disinfectant chemicals will be needed. If water is scarce, you may not have the luxury of throwing contaminated water away. The easiest thing to do is add more sodium hypochlorite or calcium hypochlorite. Just like I described previously in my many articles on disinfection. As soon as you have added enough disinfectant to have a measurable and lasting residual; then you have added enough. If you don’t add enough you will need to do it again. This will work on reservoirs of any size, all that changes is the volumes and detention times involved. The minimum acceptable concentration of a chlorine residual after disinfecting a stored water supply is 0.25 mg/L. If you have a constant level above 0.25mg/L then you know there is no bacterial growth in your water. If you are using your nose to measure the addition of chlorine, then you will be at least eight times over 0.25mg/L depending on how sensitive your nose is. I can’t smell chlorine in water until around 4.00mg/L and my wife can smell it around 2.00mg/L, as you can see the nose isn’t the best measurement tool.
Preventing contamination and treating water contamination is just as important as having a backup source of drinking water. Having large volumes of contaminated water in you home isn’t very useful, unless you are equipped to deal with it. Being able to remove contamination when you are depending on your stored water for survival will stop you from getting sick at a time when getting help will be difficult or impossible. With a little planning, and a little preparation, it is possible to keep stored water supplies clean and safe for drinking for as long as you have a supply of water stored.