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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.

Save Your Home from Fire

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.

Meet Legal Requirements

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.

Improve Water Quality

The water coming out of a properly designed 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 tank becomes a substantial treatment step.

Provide Thermal Storage and Freeze Protection

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 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 storage as a “battery,” from which electricity is extracted by running it through a hydroelectric turbine.

Enable a Smaller Pipe to Serve for a Distant Source

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 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.

Ways to Store Water

If you want to store water, here’s your options:

Source direct (no storage)—a rarely applicable but desirable option if you have a clean source higher in elevation and flow than the water uses.

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