Do-it-yourself Off the Grid: Water Pumps
Do-it-yourself (DIY), is an essential component of living off the grid. For some it’s about the independence and the feeling of self-reliance. For others it’s dealing with the hard fact that there aren’t exactly repair guys lining up to maintain custom solar, wind and water systems. In that vein, I am rolling out a new series for our off-the-gridders about a variety of DIY projects. To start things off, let’s examine DIY water pumps.
When people live off the grid and have to make their own electricity, they examine how that power gets used and how they can conserve it. Water pumps are necessary because they move water, but typically consume a large amount of electricity. However, there are pumps that you can build yourself, which don’t require any electricity to operate.
Hydraulic Ram Pumps
If you have water on your property, such as a reservoir or spring, and need to get that water to your home, a hydraulic ram pump is your best bet. These pumps, located at least three-to-five feet lower in elevation to the source, use the head pressure of the water coming from the source into the pump. It then creates more pressure in order to pump the water to a higher elevation. This is the perfect setup if you have an elevated holding tank that feeds you home and you need a way to keep that holding tank full. Ram pumps work around the clock, and have only two moving parts, which makes them extremely reliable.
In terms of how it works, Clemson University published an excellent summary:
The concept behind the ram idea is a “water hammer” shock wave. Water has weight, so a volume of water moving at a certain speed has momentum — it doesn’t want to stop immediately. If a car runs into a brick wall the result is crumpled metal. If a moving water flow in a pipe encounters a suddenly closed valve, a pressure “spike” or sudden increase appears, due to all the water being stopped abruptly (that’s what water hammer is – the pressure spike). If you turn a valve off in your house quickly, you may hear a small “thump” in the pipes. That’s water hammer.[1]
A hydraulic ram pump consists of simple plumbing parts available at most hardware stores. The most sophisticated pieces are a couple of swing check valves, which may need to be sourced at a plumbing supply house. Otherwise, everything else should be readily available. The sizing of the parts is determined by the volume of water you want to move and where the water needs to go. Detailed instructions on how to build a pump can be found on the Clemson University’s Cooperative Extension ram pump page.
Of course, nothing is all rainbows and unicorns, the big drawback to a hydraulic ram pump is that there is a significant amount of water waste. For the pump to create pressure, it allows a certain amount of water to flow through a waste check valve. Therefore, these types of pumps are best used when the source is a stream or other flowing water source. Revisions can be made to mitigate some of these inefficiencies, but there still will be a certain amount of waste. A ram pump is not the right choice if you have a limited or low-flow source such as a pond or dug well. For those sources, a DIY wind-powered pump is a better option.
Wind-Powered Water Pumps
As mentioned, if your water source is a standing source, or your water budget cannot withstand the waste of a ram pump, a wind powered pump is probably a better option. A sufficient amount of constant wind is required for wind pumps to be effective. The bigger the windmill, the better the ability to supply an entire home.
The basics behind a windmill lay in the concept of converting rotational motion into a stroking motion. The stroke ends up drawing in water from the source and pushing it out to its destination. The reason that size matters with regard to windmills is that you need the rotational mass of the windmill blades/rotor to overcome the varying strain imposed by the lifting and pushing of the water weight.
Although there are a number of YouTube videos showing how people have constructed windmills with bicycle parts or other small-scale parts, to supply a home you need to go bigger. Dick Stanley published a manual back in the 70s that lays out a fairly comprehensive instruction set on building an Arusha windmill. Arusha windmills can be built at a fairly low cost, and they can easily be maintained and repaired with common tools. This manual can be found on the USAid.org website.
(Click the icon to download the manual)
Windmills do have their drawbacks. First, as mentioned before, you need wind. Solar-estimate.org has a great calculator that helps determine if you are in a good area. It provides other information to help size a wind turbine electric generator, but the key piece is that you can enter your zip code and other basic information, and it will tell you if your area is suitable for a windmill.
The next drawback is that the wind turbine is limited on how much lift it can provide. If your property is relatively flat, and your holding tank is not elevated very high, a windmill could still work. If either of these conditions cannot be met, it might be more advantageous to increase the size of your electric power storage system in order to accommodate an electric pump.
As you can see, there are ways to transport water that don’t involve a yoke and oxen. With a little hard word and ingenuity, a system can be built that can provide reliable water to your home.
Keep an eye on Land University as we’ll be rolling out more informative DIY articles to come.
[1] http://www.clemson.edu/irrig/equip/ram4.htm