Today, I will explain the importance of a water reservoir or cistern as your home’s main water supply, and how you can store water in one. I will also discuss the basic design of one and how simple it can be made.
I have one announcement and one call to action before I get started.
Announcement: Here fairly soon, I will probably take a few days off of writing the blog because we are expecting our little Ezra to arrive soon. My wife cannot wait! In order to give her the time that she deserves, I will have to give up some time on here. If you guys didn’t know, It generally takes 2-3 hours per blog. There is more research than you may realize, and I am a slow typist. I WILL post about his arrival when it actually happens and may send out an email to those subscribed to them with a few more details.
Call To Action: Go to my National Preparedness Month Social Media Post that I have made one facebookand twitter and share it for chances to win cool survival gear! Remember, I have been pushing others to share the post that I have made, so I can track all the shares, so if you share directly from the site, or in your own share or tweet, please send me the URL, so I can ensure that I get the correct count, or you can tag my facebook or twitter pages and then I will see it.
What is a cistern? It is essentially a reservoir for holding a liquid. Most times when people think of a cistern, they think of an underground tank, or a deep well. Cisterns are different than wells in that they are liquid proof. Cisterns were the main source of drinking water in civilized areas. Many of them spanned half the area under a city or town! They were created to collect rain runoff.
Modern cisterns are much smaller and are usually used for irrigation only due to water quality issues.
Cisterns, and in our case the ones specifically used as water reservoirs, can be used above ground as well. The tank on your toilet is considered a cistern, and so is your hot water heater. They are liquid-proof tanks designed to hold and store water. So, by this logic, a water tower is also a cistern. I bring all this up, so I can explain how we will use one at our own home. So I can explain how to store water in the water reservoir.
One big key to remember when designing your cistern is that height (of the top of the water, and of the tank) equals pressure. The higher the tank and the higher the water in the tank, the higher the pressure felt at the faucet.
The next big key to remember, which in my opinion is generally overlooked by people explaining this, is isolation, isolation, ISOLATION! You need several isolation valves coming out of the tank on your supply line because if something ruptures, you may need to isolate the whole thing. You also want to install, like most homes already have, isolation valves at every water-consuming device.
Now, let’s go over basic design on city water. Chances are, if you have city water, you are in an area that a huge tank in your yard will get lots of complaints. If you can’t move, you can still have the tank, but hidden. The attic is a great place for hiding a cistern, but has loading and flooding issues.
You may have to strengthen your joists or figure out how to distribute the weight over a large area. Water weighs just over 8.328676 pounds per gallon (8 for our needs) or 997.9955 grams per liter. So if you have a 250 gallon plastic tote, that can be found pretty easily from a soda distributor, that is 2075 lbs, or about a ton. That is as much as a large truck in your attic! Don’t let that fall down on you!
The other problem with it is the potential of the tank to burst when full of water, or the pipe you place on it to leak. Now you have a flooding potential. If you are going to do this, and I feel that it has a lot of merit if this is how you must do it, have flood insurance, and ask specifically if they will cover the damage done by the tank before you get it.
So the basic design for this will be that you have your city supplied water going into the tank with a level switch to turn it on and off that will refill it as needed. When your city’s water supply goes away, you still have water… and at pressure!
In a more rural area, you can probably put a big tank outside on a tower or stilts. You can use the 250 gallon tote, or you can use a larger thank. You can also consider using several of the totes in parallel, all piped together and inlet and outlet. If you had 5 of these totes, you would have 1250 gallons of water. That is at least 3-4 days of water, or if you know that you have lost water, it is probably even more because you will be less wasteful.
In the rural area, you may also have a well with a pump. Pipe the well to the Cistern with a manual pump for a backup. Problem with elevated cisterns outside is the ability of the water to freeze. You may need many heat traces or other methods of keeping everything warm. This is why many people keep them in the ground below the frost line.
In both designs, I would recommend having at least one faucet off of the main supply, so if the cistern is gone, you still have one way of getting water.
I thought about going into details about pressure vs. elevation, but unless you specifically ask in the comments, I will not bore you.
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