I am writing this article because most of my friends are still living in major U.S. cities and I feel that this information could be very valuable to them. In a grid down situation, one of the most important items to have on hand is a quantity of stored water. According to the Rule of 3’s, in an extreme situation, you cannot survive three minutes without air, three hours without shelter, three days without water, and three weeks without food. I went off grid in October of last year, and I have learned a lot. I live on top of a mountain, and I do not have a well. Instead of my own well, I haul my water from a community well, using a late model Ford F-250 truck with a 460 cubic inch engine. The truck is a big gas hog but will haul a 425 gallon tank up the mountain. After all, 425 gallons weighs 3400 pounds, so it’s quite a load.
Because in a grid down situation, the community well, which is connected to the grid, would not work without a backup gas generator. The problem with this setup is that securing a well three miles from my home would be extremely difficult, and in a long disruption the well would require increasingly unavailable fuel. A working, clean source of potable water would also become a potential target. I needed a backup plan. In the short term, I am able to store 1500 gallons of fresh water in a holding tank. The 1500 gallons of stored water, under normal use, is equal to a six-week supply.
I recently installed a rainwater catchment system to add to my overall stored supply. I live in an area that doesn’t get a lot of rain, so water is a precious commodity. The area I live in, on average, gets only 14 inches of rain per year. Properly sizing of your water catchment system is exactly like sizing a battery bank for your solar electric system. You always want more than what you can use, before what you use is replenished. Meaning if you only get an inch of rain per month, you will want to be able to collect as much of that rain as possible. Your holding tank in this scenario should exceed what you can collect in a one-inch rainfall. If you have more rain per month, your holding tanks can be smaller.
The formula in measuring exactly how much water your roof area will collect is as follows: Surface area (in square feet) multiplied by the amount of rain multiplied by 0.623. So, if I have 1400 square feet of roof space multiplied by 14 inches of rain multiplied by 0.623 that will give me 12210.80 gallons of rainwater per year. This also would equal 872 gallons per inch of rain. A catchment system, to allow for fluctuations in weather patterns, would have to exceed 900 gallons. Otherwise, the ability to pump this water to a larger holding tank would be essential.
Some homework is also necessary when trying to calculate the amount of catchment area you will need. In a normal year, a weather pattern might change over the year. For instance in your location, does most of the annual precipitation fall only in a few months or is it spread out across the entire year? In your location will you have a very wet spring and a dry summer? How long are the winters? How much snow melt will you have once the snow falls.
If your precipitation all falls within a couple of months during the year, you may want to consider having a larger holding tank. I am located in an area where most of my precipitation will be in the autumn, though the spring has some, and the driest period is the summer. What this means for me is that I need to catch and hold enough to get through the summer and be able to not only have water for my family but also for supplemental watering of the garden.
A few of my friends that have city water also have a rain catchment system and rain barrels. In a grid down situation, you need to be able to have access to that water. Carrying your own water in buckets and trying to make it useful is a waste of energy, especially when you are most likely going to try to conserve energy, due to the possibility of rationed calories. Water weighs roughly eight pounds per gallon, so hauling all your water could quickly get exhausting. Think of all the ways water is used in your own home– for cooking and cleaning, flushing your toilet, taking a shower. All of these common, everyday uses for water would be exponentially more difficult without water pressure.
I have come up with the solution to this problem that will cost less than $200 and requires almost no plumbing skills. You will need the following items:
- Three ¾ inch diameter 5” galvanized pipe nipples,
- Teflon tape or plumbers Teflon,
- Two standard filter housings,
- One general use filter to fit the filter housing,
- One finer filter to fit the filter housing,
- Three 6’ lengths of wash machine hose,
- One 12v SHURFLOW fresh water RV pump,
- One set of hose adapters for the fresh water pump, and
- One 12 volt battery.
First, take the galvanized pipe nipples and thread them into the filter housings, linking them together so that water can flow from one to the other. Then attach the other two nipples at the other sides of the filter housings. Next, attach the wash machine hose to the nipples. Take the input side and attach it to your rain barrel valve. Once that is attached, install your filters; you want to put the standard filter in the first filter housing and use the finer filter for the second housing. Using these filters will prevent any debris from entering the pump, which would cause the shut off to malfunction. At this point thread the set of hose adapters onto the pump. Next take the hose from the other side of the filter and attach the hose to the input side of the pump. You will see the pump has a direction arrow to indicate the flow direction. Finally attach the hose to the other side of the pump and then to your outside spigot. Once that is done, make sure you shut off the water main coming into your home or install a check valve coming out of the main. If there is no check valve or the water main is not shut off, you will pump all your water into the city pipes and loose it.
Once your water main is shut off, turn on the spigot from your water catchment system and the outside spigot to your home. You can now connect the pump to the battery. The SHURFLOW freshwater RV pump is really the heart of this system. The pump I purchased for my back up system cost $90.00. It operates on 12 volts, and when it is in use will draw about 90 watts or 7.5 amp hours of battery power. The pump has a pressure switch, which will shut off the pump once it pressurizes the system to 45psi. It also has a high temperature shut off, which will prevent it from overheating and burning itself out.
Once you have the pump connected to the battery, the pump will begin to pump the rainwater or stored water into your home and pressurize the plumbing to 45psi. Once your plumbing is pressurized, the pump will shut off. The pump uses a mechanical switch to shut itself off and works on pressure, so it will not drain your battery when it is *****NOT?****in use.
When you go back into your home, you will be able to run the water in your sinks and flush your toilet, all from the RV pump. The only drawback to this pump is that the speed of the water is slower than what you would get from the city and, if you are washing dishes and someone flushes a toilet, the water pressure will drop significantly. The benefit to this system is it can be run off a car battery, which can be kept topped off by even a small solar panel. Most likely you wouldn’t be running this pump for any extended period of time, so the draw on your battery would be limited.
Your plumbing can handle the pumping of water into the spigot. In fact you can attach this pump to any part of the cold water side of your plumbing system, and it will not make a difference. Water does not have to come from the main in order for you to have water pressure. If you have water stored on the inside of your home, this can be attached to a spigot or valve anywhere in your home.
Another benefit to this system is that it can be attached to an inexpensive camping in-line water heater, and you will be able to have hot water. Because a camping inline water heater operates off a couple of D-cell batteries and can be hooked up to a propane tank, you will be able to have hot water. If you take the hose coming from the pump and attach it to the water heater then run another hose to the outdoor spigot, you can have on-demand hot water. Once the heater is installed, you will be able to switch back and forth from hot to cold, by simply shutting off the propane tank. One item to note here is that because you are heating the entire plumbing system when you connect this to your home, you will need to adjust the water heater’s temperature to a comfortable level.
For a long-term grid down situation, I would consider moving the pump to the inside of your home and plumbing a line from your catchment system into your house, as well as setting up an interior valve to attach your backup pump to. This entire system can be mounted to a board, plumbed, and ready to go in case of loss of water. If you have this prepared ahead of time, you could restore water pressure in your home in a matter of just a few minutes.