Water Storage Tank - Rainwater Harvesting

Water Storage: Water Tanks and Rainwater Harvesting

Water storage is an important consideration that any survival plan should take into consideration. Even if you are near a renewable water source such as a river or a well, utilization of a water storage tank is advisable for a number of reasons. First, your renewable water source may dry up, permanently or seasonally. Additionally, it may become heavily contaminated to the point it is unsafe even after using water purification techniques. Water storage tanks give you an extra water stockpile for an emergency situation. They can store several thousand gallons of water. Given that the average adult should drink about a half of a gallon per day, a 2,500 gallon water storage tank would provide enough drinking water for five people for almost three years. Because you will need water for purposes other than drinking (bathing, cleaning, agriculture, livestock), you should also consider a rainwater harvesting system to reduce dependency on a single stockpile water supply.

Water Storage Tank - Rainwater Harvesting

“Rainwater Cistern,” © 2009 ecologycenterberkeley, used under a Creative Commons Attribution license: http://creativecommons.org/licenses/by/2.0/deed.en

Even if you don’t have the resources or the space to build a large complex rain water harvesting or storage system, you should at least start with some basic water storage barrels to supply you and your family with water for a few weeks to a month. I recommend that you look at the water storage tanks at Portable Tank Group. They have a huge selection of different types and different sizes of water storage tanks for just about any type of water storage needs.

Water Tanks

With any water tank, safe storage is the number one concern. This means safe for human consumption and safe from unintended access by children. With regards to safety for human consumption, the water storage tank should not allow any light into the tank. This is because sunlight causes growth of algae in the water. These microorganisms can cause disease if ingested. Additionally, the tank should be tight and secure so that outside debris, animals, and insects cannot get inside. Otherwise, the water will get contaminated. With regards to safety from unintended access by children, make sure that you at least have a locking mechanism for the opening at the top of the tank. You might also consider having a tall tank so that it is more difficult for children to access the top.

Here are the main things to consider when looking into water storage tanks:

1. Tank Color

– The only reason I mention this is because of sunlight penetration and water temperature. Make sure that the tank is not susceptible to light penetration. This means that it should be a darker opaque color. However, dark colors can cause the water to warm up more than desired in summer months. A good strategy is to paint a dark tank white so that light cannot get through, but the white outer layer helps to reflect the sunlight and thus keep the water somewhat cooler.

2. Tank Material

– There are a lot of different types of water tanks for sale. Tank materials you will encounter as you do you research include corrugated steel, galvanized steel, concrete, wood, fiberglass, and plastic. Wooden tanks are not very common anymore because they are susceptible to leakage. Concrete tanks are very durable, but may be impractical for you. The metal tanks are also very durable, but will cost more than the plastic models. Plastic water tanks are very common because they are affordable, and lightweight. If you are looking for a portable water tank, one that can be moved easily, plastic water tanks are probably your best bet.

3. The Openings

– The main openings on a water tank are the inspection port, the inlet, the outlet, the vent, and the overflow.

a. The Inspection Port

– This is an opening that allows you access to the tank for maintenance and inspection. The inspection port can also be used as the main inlet. Always keep the inspection port locked so that small children are not able to open it.

b. The Inlet

– This is where the water enters the tank. By utilizing what is called a “calming inlet,” you can reduce the chance that incoming water will agitate any sediments that have settled at the bottom of the tank.

c. The Outlet

– This is where the water exits the tank before being treated for its final use. The outlet should be located at the bottom of the tank, but should be a few inches above the very bottom. Otherwise, sediment is much more likely to come out with the water. If you prefer to get the water that is siting on the top of the water supply, you might consider using a floating tank pickup, which utilizes a floatation device and allows you to always be accessing the top few inches of water, even though the outlet is at the bottom of the tank.

d. The Vent

– A vent is important because it will prevent a vacuum situation from taking place. The vent is a gooseneck pipe that comes out of the top of the tank and bends down so that the opening is facing the ground. This reduces the risk of contamination through the vent. Make sure there is a screen or mesh material over the vent opening so that insects and small animals cannot gain access to the tank.

e. The Overflow

– An overflow is needed in case of a heavy rainfall. The overflow should be slightly lower than the inlet. Some overflows drain from the bottom rather than from the top. Either one is fine, but if your overflow drains from the bottom, make sure that there is a hole in the outflow to prevent a siphoning effect from occuring.

4. Water Tank Placement

– Once you have set your tank up and filled it with water, it is going to be very difficult to move it. Therefore, you should make sure you get it in the right location. Consider, among other things, nearness to point of use, elevation for gravity flow, nearness to collection method (see rainwater harvest system below), and the lay of the land.

5. Aboveground vs. Belowground

– You should decide if you are going to use an aboveground or a belowground water tank. Advantages of underground water tanks are that the water temperature stays constant year round and they are not susceptible to sunlight. The disadvantages of underground water tanks are that they are more expensive, they are susceptible to land shifting and thus cracking and leaking, they can get contaminated from dirt and runoff easier than an aboveground tank, and you will need a pump to get the water to its intended use. Disadvantages of aboveground tanks are that they are susceptible to sunlight and algae contamination, and some consider them to be an eyesore. Despite these disadvantages, my personal preference is for aboveground tanks because they can utilize gravity flow, they are cheaper to install and maintain, and all things considered, they are less susceptible to contamination. I personally don’t consider them to be an eyesore.

There are a lot of different types and sizes of water storage tanks to choose from.  Everyones needs are going to be different, but for a retreat setting with a survival group of five to ten people, I would recommend starting with one 2,500 gallon tank and then allowing for the expansion of the system to accomodate adding more tanks if desired.

As you select your water storage tank, you should also consider whether or not you want to employ a rainwater harvesting system.

Rainwater Harvesting:

Rainwater harvesting is the process of collecting rainwater for human consumption and use. This system should work hand in hand with your water storage tank. A rainwater collection system is a good idea, especially if you are not close to a renewable water source. Rainwater can be used to supplement your existing water storage supply.

Components of a Rainwater Collection System:

1. Catchment Area

– The catchment area is the area that “catches” the rainfall. This is typically going to be the roof of your house or another building. The main considerations here are what type of material is used for the catchment area, and what kind of slope is employed. Some materials are more conducive to rainwater harvesting. Metal is usually the best because it allows for the least amount of debris and microorganisms to mingle with the water supply.

2. Conveyance

– The Conveyance area refers to the gutters and downspouts. The gutters channel the rainwater toward the downspouts, which in turn, guide the water through pipes into the storage tank inlet. Gutters and downspout should be wide enough to account for heavy rainfalls. A good rule of thumb is at least 5 inches width for the gutters and one square inch width of downspout area per 100 square feet of catchment area space.

3. Treatment

– Treatment of rainwater refers to the several different points at which pollutants are removed from the water in order to make it safe for human consumption. Treatment can be divided into two main areas: 1) Pre-Tank Treatment, and 2) Post-Tank Treatment.

a. Pre-Tank Treatment

– The goal at this stage is to purify the water as much as possible before it makes its way into the tank. The water coming from the roof can have debris such as leaves, sticks, dirt, bird feces, etc… You want to initially divert and screen as much of this as possible. This can be done by employing a diverter chamber transition fitting to the downspouts. This technique allows you to divert the initial flush of water at the beginning of a rainfall. The first flush from the roof is going to be the dirtiest, but after a short while, a lot of the gunk and contaminants will be washed away. You should also use a screen transition in conjunction with the downspouts to filter out larger debris. If you have screens, you should check them often to make sure they are not clogged. Clogging can be prevented by using a special type of angled screen.

b. Post-Tank Treatment

– Post-tank treatment refers to the stage in which water is purified and made safe for human consumption. The intensity of treatment at this level will depend on the intended use of the water. Obviously, drinking water gets the most attention and treatment. However, water that will be used for agriculture probably doesn’t need much treatment at all. For water that is going to be used for human consumption, you should use a multi-barrier approach. The first barrier is the filtration barrier. This is like screening, but on a much smaller scale. Next is the disinfection barrier. At this stage, the goal is to kill microorganisms that may be in the water. By using a combination of chlorination and UV light, you should feel pretty safe that the water that is safe to drink.  For more on water purification, see The First Necessity For Survival: Water Purification

4. Distribution

– Depending on whether you will simply rely on gravity flow or whether you will use the water indoors under a pressure system, the distribution system can be quite complex. If you are planning on implementing a pressure system, the distribution system should be completed by a licensed plumber.

In conclusion, water storage tanks and rainwater harvesting systems can be one of your most valuable assets in a survival situation. Figuring out the logistics of your water storage needs should be at the top of any survival plan.

Even if you don’t have the resources to build a large complex reain water harvesting or storage system, you should at least start with some basic water storage barrels to supply you and your family with water for a few weeks to a month.

As mentioned above, I recommend that you look at the water storage tanks at Portable Tank Group. They have a huge selection of different types and different sizes of water storage tanks.

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  1. […] important when collecting rainwater to fill your tank. If the water comes through your downspouts it’s a good idea to use a diverter until the rain has washed away the layer of dirt and contaminants that have been sitting on your […]

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