An ideal off-grid water system would draw water from an abundant, clean, year round spring or creek. There would always be enough water supply to meet demand, and there would be no concerns about extra water for fire protection or emergencies. But since few of us are blessed in this way, nearly all water systems include some form of storage, most commonly a water tank. Even if you get your water from a municipal water system, you may want to store water at your home for fire protection or emergency preparedness.
Water storage can be used to:
We’re going to consider each of these reasons to store water:
The most common function of water tank storage is to cover short-term use flows that are greater than the flow of the water source. For example, a tiny, one gallon-per-minute spring supplies 1440 gallons a day. This is several times more than most homes use in a day. However, almost every fixture in the home consumes water at a faster rate than 1 gallon per minute (gpm) while it is turned on. Even a low-flow shower head uses about 1.5 gpm.
By using water stored in a tank, you can supply water to the shower faster than it is flowing from the spring. On completing the shower, the water will be coming in faster than it is going out, and the tank level will rise back up.
If you had a 10,000 gal tank, you could run a 100 gpm fire hose—creating the kind of blast used to bowl over hostile crowds—on the stored water from this tiny spring, for an hour and a half! Hopefully the fire would be out by then, as the tank would take several days to refill.
In some circumstances, your storage needs will be affected by variations in the water supply. For instance, if the supply is rainwater, you will need enough water tank storage to make it through the intervals between rainfalls. A six-month, rainless dry season requires a heck of a lot more storage than the most common kind of variable supply—a well pump that cycles on and off.
If you have a well that taps stored groundwater, a water tank will save wear and tear on your pump, because the pump won’t have to switch on and off every time you open a tap.
In many places, the water supply chain from source to tap is long and made of many delicate links. If a cow steps on the supply line, a pump breaks, a wire works loose, the electricity goes out, the city misplaces your check, or there is a natural disaster, your water flow could stop. By locating your storage as few chain links away as possible from your use point, a large measure of security is added.
Designing a system to be effective for combating fire can change its specifications radically. To put out a fire, your stored water needs to be available at a flow rate many times greater than normal.
Sometimes you may be required to install water storage simply to meet a legal requirement. On the other hand, you may be able to trade increased water storage for slack on a different legal requirement. For example, if you provide a large amount of water with good pressure that is reserved for fire emergency, a sprinkler system, and/or a hydrant, the fire department might allow you to build a narrower driveway with a smaller turnaround further from the house than they would otherwise—thereby saving you a fortune.
The water coming out of a properly designed water tank can be of significantly higher quality than the water that goes into it. This is mostly due to attrition and settling. Add an ozonator, and a water tank becomes a substantial treatment step.
Water has higher specific heat—stores more thermal energy per unit of weight—than any other common material. A large thermal mass of water stored in a water tank within a solar greenhouse or home can help to keep it cooler in the day and warmer at night.
Also, as water changes to ice, it radiates a tremendous amount of stored energy. Imagine how much gas it would take to melt a water tank-sized ice cube; when water freezes, it releases this same amount of energy. This is why irrigating for frost protection is effective. The stored energy in water can prevent a water tank or nearby components from freezing (though in the coldest climates this may not be sufficient).
Evaporation consumes even more energy, which is why swamp coolers and cooling towers are effective. Water is also an effective heat transfer medium.
Finally, in rare instances it can be economical to use elevated water tank storage as a “battery,” from which electricity is extracted by running it through a hydroelectric turbine.
If the flow of your source exceeds the peak demand, you can connect to it directly without storage. However, if the source is distant, it may be cheaper to run a small pipe to nearby water tank storage, and a big pipe from there to the use point. The small pipe would be sized to the average use, the big pipe to the peak use. The savings in materials and labor from running a smaller pipe over most of the distance can often pay for the storage and then some.
South African conditions, off-grid and in urban areas, make on site water storage very desirable. Plastic or ‘poly’ water tanks are usually the easiest type of water tank for homeowners, businesses and farmers to obtain and install.
JoJo’s superior plastic water tanks and 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.
JoJo Tanks (South Africa) offer a wide range of plastic water tanks and chemical tanks to suit every household, business or agricultural need. See JoJo Tanks VERTICAL TANKS, HORIZONTAL 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.
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